Simple reskin?

I want to make a simple reskin, and I want to use paint.net. How can I do this in a super-noob-proof way?

I want to reskin a thing or two but I am unaware of how to simply change a few colours and add a picture :saddowns:

I suggest you get GIMP, as it is just as powerful as Photoshop, plus get VTFEdit.

Follow this video:

This helped me a lot, i figured out yesterday how to totaly reskin and make materials for Hammer. The video told me most of everything this will help with materials/skins (Photoshop works well for me)