What exactly is a Prelude Tune-up

if i took my prelude to a shop and asked for a tune up what would he do to my prelude and how much should i expect to pay. also does it take any mechanical knowledge at all to replace spark plugs and spark plug wires cause it looks pretty simple...

It takes almost no mechanical (well, maybe a tiny bit) knowledge at all. A full tuneup, like what you would do after immediately buying a used car, would involve something like:

New Spark Plugs (or just check them)
New Spark Plug Wires (or just check them)
Coolant System Flush
Oil Change
New Oil Filter
New Dizzy Rotors/Caps (or just check them)
Tire Inspection (rotation if need be)

If doing it yourself for the first time, it should take no more than an afternoon and evening.