i only found out recently too well you just go File>>creat fable mod package>>and drag the edited files from the menu on the left into to the box that appears.
dosnt matter i dont think i edit them in photo shop so i geuss im doing them in PSP format but you can always change it when your saving the files youve edited
well u can go Adjust>> hue saturation>> and from there change master to the colours you want to change unless you want to change the master colour but i would suggest you just play around with it for a bit (and make a copy of the texture)