I am doing this christmas thing and I need a elf costume does anyone have a idea how to MAKE a elf costume or what to use? Also any ideas on how to make Elf ears?

You can probably purchase a elf pattern at any fabric store especially around this time of the year. If you're doing more of the putting different parts together type costume try getting a green skirt and cutting triangles out of the bottom. Add a green top, a red belt and either a red vest or a red multi point star bib type thing (you can make of just a piece of fabric with a hole in it). Oh! And some candy cane like socks.
The hat and the shoes, you are on your own.
The ears? Think of them not as Elf ears but Vulcan ears! The Star Trek fandom is huge and vast. Try comic stores, toy stores, pawn shops, costume stores, yikes I've even seen them in gas stations before (ok... gas stations in Vulcan... ). You can probably find a pair for under $5. If you also know of a forum for people in your city ask them, chances are there are at least a handful of Trekkies on the same forum.