Building an ebb and flo setup is probably one of the easier ones to build because you don't need to run a bunch of tubing.
The mechanics of it are pretty simple really. The reservoir (which should be below your plants) will have a water pump in it. The water pump pumps water from the reservoir up into the tray with the plants, then when it gets about 3/4 full, you should have the water drain back to the reservoir.
checkout this article, it guides you along making both a drip system, and an ebb and flo system.
Here are pictures from their article of a basic ebb and flo diagram.