Can someone help me with Gimp 2?

Ive just learnt to do backround changes, and I would like to know how to put a shadow in to make it more real, and to also make it more real by like, making the grass or whatever cover the hooves slightly, if you understand what I mean?

Also, I would like to know how you can like, put on fog and whatnot maybe?

And a big one please; How do I put several images on one backround?

Thank you, can someone with more experience please help me?

Bumppppp!

I know this thread is uber old but seeing as no one replied I'd be willing to help if you still wanna know if you pm me everything you wanna know I'll make a tutorial for you (don't worry I'll explain everything in it) so yeah let me know if you still want help

Please tell me too!!

Me three