HI there, it really isn't as scary as you think it will do.
Firstly you will need a regulator (has the gauges on it), then a solenoid if you want your CO2 to be turned off automatically, a bubble counter, a check/stop valve and then a diffuser.
The order you attach things are regulator to FE, solenoid to regulator (if not already attached), tubing that leads to a stop valve, more tubing leading to a bubble counter, then more tubing that leads to the diffuser which you place in the tank as far down as possible, so that it gives more chance for the CO2 to diffuse through the whole tank.
When you are attaching the reg to the FE, firstly unscrew the spray horn bit, then attache the regulator to this. use a wrench for this and do it as tightly as you can. Then take the pin out of the handles and squeeze the handles down. You shouldn't hear any sound like air escaping (leak if there is), and you should see the dials in the gauges have readings on them.). Then get some masking tape and wrap it around the handle to keep them squeezed together. Then attach everything else, check for leaks as well (full description of that earlier on in this post), place the diffuser into your tank and then adjust the bubble flow with the needle valve, which is usually attached to the regulator.
hope that helps. Sure I've forgotten something along the way, but I know how much of a mine field it looks like when you are just starting, and it can get depressing if it doesn't work, but is so easy when it does.