Hello all. I recently downloaded GIMP, and I'm completely lost on how to utilize the program to add some effects. I wanted to make signature-ish images for forums by taking renders, but I'm not sure where to start. Is there an online guide or reference that I can use to learn the program? I read the entirety of the user manual, but I still haven't really found anything useful regarding the subject.

Picture related: It's the type of images that I'd like to create (the effects anyway).