want to layer a picture in Gimp

I am unable to layer a picture on another picture by using Gimp with no success. Does anybody know any tips for the same. Thanks in advance

Have a look here that might be able to help you out.

Nice link but i have already seen that before. So over the few days i started fiddling with softwares & various sources on my own. The sites that i visited taught me very execellent methods like masking, background erasing & many more that really proved to be very useful. The tips that were mentioned were pretty easy & anyone can understand it quite easily. Now i am almost finish in the process of drawing Tux's arms around the guitar with my own. Check out
this as i figured this on my own.

Thats awesome bro, what exactly did you use for the layered picture?