First, get Gimp
Second, set up tje dimensions for your texture. (Assuming you know the correct ratio.)
Third, what you want to do is hover your cursor over "Filters" and try to find a tool that says "Create noise" or something like that.
(I dont remember which option it was under.)
Fourth, a window should appear. Stretch the noise to the point it'll look like bands. Finalize the changes.
To color it, go under tools or colors, and find an option that says colorify. Select yer' color and you are done.