Jim,

Assuming you have the screws holding the drum in place removed, the next step is to back off the slack adjuster. If you haven't caged the emergency brake do that and then back off the slack adjuster by lifting the sheet metal disc and then turning the square adjuster counter clockwise.

If the drum is stuck to the hub as Ken describes give it a whack.

When re-assembling use never-seize on the brake drum screws because that will save a lot of effort the next time. They are usually a pain to loosen. I urge you to look further into using lube on the wheel studs. As far as I know that is not recommended.