Ringing Ceders

I have recently started skateboarding. I thought that it was just for skater guys. But one of my friends started doing it and got me into it and I have really been having a lot of fun. I would like to do it even more often. I have been searching for free plans to build a skateboard ramp online. I would like to build one for my yard but I do not know how to do it. I figure that someone out there has done it and hopefully they have put their plans on the Internet so I can copy them!