Download GIMP, it's like Photoshop but free. I generally make my bio images 800px wide for Chaturbate, I'm not sure what Cam4 uses. If you need tutorials on how to do certain things, DeviantArt has a lot of them. You only really need to pick a font though.
Make sure the text stands out, don't make it a color hard to read. Here's an example of one I made myself for Chaturbate. I downloaded a free-to-use font from Dafont.com to shake things up lmfao.
