It appears you have your arrows backwards. The arrows for the drains should be going into your overflow. Homework time, read this link-
http://www.beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system.aspx
That will tell you everything you need to know and how to set up your overflow. You cannot have a better system then this one.
As for your returns, besides the arrow going the wrong way, thats the right idea. One pipe out of the pump, when you get to the bottom of the tank split it, either with a T or the Y I posted last page, right up to the two holes you need to drill. If you post a shot of the back of the tank I'll draw it for you, a shot straight on it.