Hey Kilo how long have you been using GIMP??
I can tell you are really trying, Thats good!!!just remember its not all going to come together over night!! You need to start with the basics of your program (GIMP) Things like re sizing and keeping perspective, masking, color adjustments, layer styles ect, ect..... It looks like when you re sized the render you lost perspective on it!!! TEXT is a lot better just be careful you dont get too fancy with it!!! I know you will be getting a lot of different feedback coming at you and you dont have to get it all right at once, just take 1 or 2 thing and work on them till you have it down!! Then move on to the other feed back you get.....just dont get discouraged, we are here to help you get to where you want to be as a designer!!