

What do you want to do with your poster? Will this be used as a meme or will it actually go to a printer or be displayed on a high-res screen? If it’s just a meme thing, any image creator AI will do. Most of them have free options.
If this will actually go to a printer, you’ll need high resolution images and would do well to design it in a vector format, SVG for open source software: Inkscape is free to install on computers, vector-ink is a thing for mobile and the web as well. Adobe Illustrator for the corporate expensive route. Big file sizes work better on a good computer so YMMV.
What you need is help, not AI. If paying a designer is out of the question, look for the most design savvy person in your family, friends, or in your neighborhood. Maybe you can comp them a meal in exchange for making this look good.
You can use AI image generators to make background images. Just check the licenses if you’re okay to use their stuff in a commercial setting. AI is still largely dog shit at handling real text in images. That’s why I wouldn’t recommend going this route for you here. You have a lot of text.