First, you need to pick a tool. There are many options, but they most­ly fall into a few main cat­e­gories.

Mid­jour­ney: This one is very pop­u­lar and known for cre­at­ing artis­tic, high-qual­i­­ty images. It has a spe­cif­ic, rec­og­niz­able style that peo­ple like. For a long time, you had to use it through a chat app called Dis­cord, which can be a lit­tle strange if you've nev­er used Dis­cord before. But it's very pow­er­ful once you get the hang of it. It's good for cre­at­ing things that look like paint­ings or detailed illus­tra­tions.
DALL‑E 3: This is the mod­el made by Ope­nAI, the same com­pa­ny that makes Chat­G­PT. Its biggest advan­tage is that it's often built into oth­er prod­ucts, like Chat­G­PT Plus and Microsoft's Copi­lot. This makes it easy to access. DALL‑E 3 is very good at under­stand­ing nor­mal sen­tences. You can just describe a scene like you're talk­ing to a per­son, and it usu­al­ly gets what you mean. This makes it a great choice if you're just start­ing out.
Sta­ble Dif­fu­sion: This one is a bit dif­fer­ent. It's open-source, which means the code is pub­licly avail­able. You can run it on your own com­put­er if your machine is pow­er­ful enough, which gives you a lot of pri­va­cy and con­trol. It's also the foun­da­tion for many oth­er AI image web­sites and apps. Sta­ble Dif­fu­sion gives you the most con­trol over the out­put, with lots of set­tings to adjust, but it also has the steep­est learn­ing curve. It's for peo­ple who want to real­ly get into the tech­ni­cal details.

For your first time, using some­thing like DALL‑E 3 through a free ser­vice is prob­a­bly the eas­i­est way to start. You just type what you want to see into a box and see what hap­pens.
Now for the most impor­tant part: the prompt. The pic­ture you get is only as good as the instruc­tions you give it. A vague prompt will give you a gener­ic, bor­ing image. A detailed prompt will give you some­thing much clos­er to what's in your head. Learn­ing to write good prompts is the main skill you need to devel­op.
Let’s break down what goes into a good prompt. Think of it like build­ing a descrip­tion lay­er by lay­er. The key ele­ments are the sub­ject, the style, and the details about com­po­si­tion and light­ing.

The Sub­ject: This is the main thing you want in the pic­ture. Don't just say "a dog." Say "a hap­py gold­en retriev­er pup­py." Don't say "a car." Say "a red 1960s con­vert­ible sports car." The more spe­cif­ic you are, the bet­ter. Tell the AI what the sub­ject is doing. Is it run­ning? Sleep­ing? Look­ing at the cam­era? Give it con­text. "A hap­py gold­en retriev­er pup­py chew­ing on a toy on a green lawn."

The Style or Medi­um: This is a huge fac­tor in how the final image looks. Do you want a pho­to­graph? A car­toon? An oil paint­ing? You have to tell the AI. Here are some com­mon styles you can use:

Pho­to­re­al­is­tic: This tells the AI to make it look like a real pho­to. You can even spec­i­fy the type of cam­era or film, like "pho­tographed on a Canon EOS R5" or "shot on Por­tra 400 film" for a vin­tage look.
Oil paint­ing, water­col­or paint­ing, pen­cil sketch: These tell the AI to mim­ic tra­di­tion­al art forms. You can even men­tion spe­cif­ic artists, like "in the style of Vin­cent van Gogh."
Ani­me style, Stu­dio Ghi­b­li style, Pixar style: If you want a car­toon or ani­mat­ed look, nam­ing a spe­cif­ic style helps the AI know what you mean.
3D ren­der, dig­i­tal art: These are for more mod­ern, com­put­er-gen­er­at­ed looks.
Line art, vec­tor graph­ic: Good for sim­ple, clean illus­tra­tions.

Com­po­si­tion, Light­ing, and Col­or: This is how you con­trol the over­all feel of the image, just like a pho­tog­ra­ph­er or direc­tor would.

Com­po­si­tion: Do you want a "close-up shot" of a face or a "wide-angle shot" of a land­scape? Maybe a "bird's‑eye view" look­ing down on a city? Use these terms to frame your scene.
Light­ing: Light­ing changes the mood com­plete­ly. Try using terms like "cin­e­mat­ic light­ing," "soft morn­ing light," "dra­mat­ic stu­dio light­ing," or "gold­en hour" for that warm glow just before sun­set.
Col­or: You can guide the col­or palette. Words like "vibrant col­ors," "mut­ed earth tones," or "mono­chro­mat­ic black and white" will have a big impact on the final pic­ture.

Let's walk through build­ing a prompt from a sim­ple idea to some­thing spe­cif­ic.
* Ini­tial Idea: A knight.
* Prompt 1 (Vague): A knight. This will give you a very gener­ic image of a knight, prob­a­bly stand­ing there doing noth­ing. The AI will make all the cre­ative choic­es for you.
* Prompt 2 (Adding Sub­ject Detail): A weary knight in battle-worn steel armor, holding a large sword. Now we have more detail. The knight isn't just a knight; he's tired and has seen com­bat.
* Prompt 3 (Adding Style): A weary knight in battle-worn steel armor, holding a large sword, epic fantasy oil painting. This com­plete­ly changes the look. It's not a pho­to any­more; it's a paint­ing with a spe­cif­ic, grand feel­ing.
* Prompt 4 (Adding Light­ing and Com­po­si­tion): A weary knight in battle-worn steel armor, holding a large sword, epic fantasy oil painting, standing on a misty mountain top at sunrise, dramatic lighting, wide shot. Now we have a full scene. We know where the knight is, what time it is, and how the shot is framed. This prompt will pro­duce a much more inter­est­ing and spe­cif­ic image than just "a knight."
As you start mak­ing pic­tures, you'll run into some com­mon prob­lems. This is nor­mal. All the AI tools have their quirks.
* Weird Hands and Faces: AIs have his­tor­i­cal­ly been ter­ri­ble at draw­ing hands. They might give a per­son six fin­gers or a thumb in the wrong place. They've got­ten bet­ter, but it's still a com­mon issue. Faces can also some­times look dis­tort­ed or strange, espe­cial­ly on peo­ple in the back­ground of a scene. If this hap­pens, one fix is to regen­er­ate the image. Just run the same prompt again and you'll get a dif­fer­ent result. You can also add more detail to your prompt about the hands, like "hands rest­ing on a table."
* The Image Doesn't Make Sense: Some­times the AI gets con­fused, espe­cial­ly with com­plex prompts where lots of things are hap­pen­ing at once. You might ask for a per­son rid­ing a horse and find the per­son is some­how merged with the horse. When this hap­pens, sim­pli­fy your prompt. Focus on one main sub­ject and action.
* Gib­ber­ish Text: If you try to include words in your image, like a sign on a build­ing, the AI will often write non­sense. It's try­ing to cre­ate the shape of let­ters with­out under­stand­ing what they mean. The best solu­tion for this is to gen­er­ate the image with­out the text and then add the words your­self lat­er using any basic pho­to edit­ing soft­ware.
The key to get­ting good at this is iter­a­tion. Your first prompt is almost nev­er your last. You start with an idea, gen­er­ate an image, and see what the AI gives you. Then you adjust. Maybe the light­ing is wrong, so you change that part of the prompt. Maybe the subject's expres­sion isn't right, so you add an emo­tion like "a smil­ing woman" instead of just "a woman." You tweak, regen­er­ate, and tweak again until you get clos­er to what you want. This process of refin­ing your prompt is where the real cre­ativ­i­ty hap­pens. You are guid­ing the tool to your vision. It takes some prac­tice, but it's a straight­for­ward process of tri­al and error.