Yes. Like everyone has suggested, the best way is always to start off with the simplest thing, and work your way through the basic possibilities...

Firstly check that there is power in the battery. You can do this using a test meter.
If the battery is as you say fully charged, check the fuses. All of them.
If those are okay move on to the wiring, making sure that you have wired everything back up properly. Remember that on some cars the positive pole of the battery has more than one wire going to it; have you made sure that they are all in place and that the connections are tight?
If possible check that the starter motor is ok... the car wont turn over, so suspect this.

As far as anything more complex than those simple checks I can only advise you get a mechanic, or at least a mechanic friend to help you, as things can get a little mind boggling from there on. (for my level of experience anyhow)

Above all - good luck, take your time, dont overlook the obvious (i.e. have you tried a *known* good battery) and enjoy.

P.S. When you get your replacement car, the one you intend to keep, I strongly advise you get a workshop manual; as they explain the ins and outs of the paticular car, as opposed to mechanics in general.

Hope you have some joy.

Tony. Volvo 440 1.8i