I was just wondering if there was a picture tutorial or video tutorial out there that i missed that shows how to make the skate ramps out of walls
Look for tutorials about making banked turns and hills on race maps, I know they exist. These should give you some pointers on the same skills you'll need to make "skate ramps."
Obviously, you need to interlock. It is really just trial and error. YouTube - Halo 3 Racetrack Tutorial::Banked Turns
more or less trial and error like Whats A Scope said, but you can try to use different slanted object to create a brace for the ramps
Probably the best way to make the skate ramps is to use different angles of the walls and then put them all together. At most I would use 10 walls for 1 ramp. Try not to over do it though.