Banner issues, can you help?

I've been trying to design a banner for days now and it's driving me mad! I have two image programs; PhotoFiltre and Gimp but I'm still having trouble doing what I want to do.

I've basically got all the elements, I have the background all done and the title and everything, all I need is to transfer an image onto it and remove the background so it's cut out. I'm not explaining it well, I know, but hopefully if I can get someone's help I can explain it better.

I've been looking up tutorials and how to's for a couple of hours now and I just can't get the damn hang of it. The tools in Gimp are overly complicated and I just can't wrap my head around it and the tools in PhotoFiltre aren't giving me clean enough lines, it's rather messy.

My banners are normally pretty basic and I usually avoid doing stuff like this so I can do them myself, but this time I need to use an image without it's background and I'm just really struggling.

Please help...?