Put 'er together
I think at this point you should be able to figure out how to get this guy together...
Stick the tabs in the sockets, tuck your wires in and stick the top on. The back plate (with the pots and the buttons) is just a wee bit taller than the main stand offs. When you tighten on the top plate, the back plate will be held snug.
You may also want to take a quick look into the rectangular hole in the back plate. This is the access port that allows you to get your FTDI board or cable into the FetaDuino to program it. It is quite likely that some of your jumper wires are in the way of this hole. With some kinda sticky-thing, encourage these wires to get out of the way.
Rocket Brand Studios
Link to Zip File of Examples
Easy Transfer Library