If you're in Logic 8 read chapters 25 & 29. that should get you started.
Otherwise look up Ultrabeat and EXS24. That's what's in Logic.
Alternatively, you can purchase any number of Drum Plugins. (do a search here in R.O. for more info already discussed)
enjoy

Many synths will have sounds on them that are simulating/sampled drums. Use a keyboard and quantize the track. If your'e not a drummer, make sure you listen to other drummer a lot to get an idea and feel for how your track should sound (less is often more!). I like to have separate tracks for kick, snare, hi-hat and cymbals. Or just play a musical sounding pattern. But quantization is your friend for sure :)

Redrum in Reason is excellent, especially for Electronica and Hip Hop. Battery 3 has some really good quality replications

assuming you are pretty much going from scratch...

here is what works for me and its fairly quick to get a drum track up.

get a good vst kit/sample set or use what you have on hand and put it on a midi channel

open a midi editor and by hand lay out a 4 bar drum measure that has the basic beat of the part you are working on. drop all the kick, hat, snare etc in there until it sounds happening. cut and past that 3 more times. change a little something in each 4 bar section. glue that together. do a little humanization on the quantize. now you will have a 32 bar drum section/loop. cut and paste those and add fills or change ups at the end of each 16-32 bar section.

do your intros, bridges or breakdowns in a similar fashion. you can have a fairly natural sounding track pretty fast.