Hi,
The drive side ( *usually* the right hand side of the bicycle) is the right side of the wheel.
Rear wheels only :
Where you need to dish the wheel ( ie set the rim closer to the drive side hub flange ), the spokes on the left side (non drive) are longer by between 3 turns of the nipple and 6 turns. You can use different length spokes with the longer ones on the left. Or, if your spokes fit well near their mid range, you can get all the adjustment using all spokes of the same length, by tightening the drive side by 3 or so turns before reaching final tension all over.
Note: the most common mistake made by beginner wheel builders, is to not set the pattern correctly around the valve hole. Its easiest to get it right by fitting up the spoke adjacent to the valve hole first, then after the first round (of 8 spokes in the case of a 32 wheel) rotating the hub so the first spoke goes away from the valve, before crossing and fitting the next 8 (on the same side).
Then turn the wheel over and fit the other adjacent spoke, its 7 mates, then the final 8.
That way the valve will have the most access space.
Good luck !
Bobthe....