I can't really remember how I got it, but me and a friend got it at the same time and made stuff. You can see the results in my portal submissions (Hero number one and the Soldier one (my friends)).
Then me and another friend got into it together to and he helped me a bit. I made some crappy stuff, but it was fun and alot of them are quite long (I have a 4 minut-ish sequel to Hero number one).
Theeennn.. I think I got into doing game sprites (not Gif sprites) because there easier to make on a smaller scale, and there just fun to whip out.
I didn't use tutorials or anything, because i'm not very good at following written instruction as my mind tends to drift.