If you're a completely noob, I suggest you play with some no-code or low-code open source platform first. You can check out mine called AINIRO Magic Cloud. 100% open sauce. Alternatively, use N8N or something similar. the idea is to first understand prompting, system instructions, messages and such - For then to later go into "code mode" where you can duplicate similar results.
As an additional bonus, since it's open source, and .Net, you can peek into the code to see how I've done stuff, and such learn "how to do AI in .Net" - If that's your goal ...