Form-Generated Image..?

Hello; I'm new to this comm and fairly new to php. I'm very sorry if this is a ridiculously stupid question, but I'm not sure where to start with this (and Google/PHP's help articles are no use).

I basically just want to create something like this - where you fill in a form and an image is generated based on your responses/entries. (Although I'd like to do one mimicking a Facebook profile, since Livejournal refuses to allow div/style commands on user bios.)

I promise I'm not a simpleton and I'm not asking to be walked through the whole thing - just an idea where to start (some sample code would be marvellous) would be lovely.

Thank you very much in advance!