I put a dinky example on the pbworks website in the software information folder. This is a KiCad project for a simple LED flasher. I saved a "before" and "after" version of the pcbnew files so that you can play with creating .dsn files, running the autorouter, creating the .ses files, and importing back into pcbnew.
The default for the autorouter is that horizontal traces are on one plane and vertical traces are on the other. You can see that it did that even though it could have put all the traces on one plane. You can play with this as well as setting the trace width and clearances by netclass.
Michael