Anyone knows tut's to making....

I got Inkscape, Photoshop and GIMP; but that's it. I know the basics but where cn I find "how-to's" and tutorials for making wallpapers like these with the three applications above

http://www.box.net/shared/lhl8i15jaj

I would also like to know how to make a PortableApps splash screen (without the logo ofcourse). I especially like the green RegShot one.

Thanks a lot,
Regards,
Mikaeel.