Scope request

Hi guys I have this scope overlay but for some reason every time I get it in game it get screwed with random artifact and strange color. Can somebody finish it so it can work in the game?
Note : This is just the PNG file which only tell how the scope looks like
PS: I use GIMP and the image is from GIMP too.

Well, I guess I coud try but now I can't.

Well, if you look at the tutorials here you find out how to use it.
Also, remember to edit the alpha channel so you make your scope visible and what to hide.