This is the same render you used last time, right?
And it's much better than the last time. *_*
You improved placement of the render. Last time, if I remember well, the render was too stretched or something like that. Also you payed attention to colors this time.
Nice improvement. *_*
I also use GIMP and I searched for tutorials on deviantart.com. And well, for a start you can find ok tutorials like this
You must be registered for see links
, till you are not familiar enough with GIMP program. When you know GIMP good enough you can use not strictly tutorials for GIMP.