Just to chip in here - your best option is requesting it from an artist in the Sig Shops. They're experienced, and they already have the tools needed.
Otherwise, do try and get hold of Photoshop. A free (Open Source) alternative would be
GIMP. If for whatever reason you can't download new software, Paint works in a pinch.
Use the Magic Wand tool if you just want something rough (Tutorial
here), but for detailed/high-quality work (such as rendering/cutting) I'd suggest the Polygonal Lasso tool (Tutorial
here) and zooming in to around 800 - 1200%.
After you've selected the part of the first image that you wish to keep, it's a simple matter of copy-pasting it where you want it on the second image. Hope that helps!
