How do I get the globe off the ceiling fan to change the lightbulb? It does not seem to unscrew from the bottom.

Can you give us a model number or style? Normally you should see 3 or 4 small brass screws just above the globe but its hard to explain further not knowing the model.

In most cases if the glass has no visible thumbscrews you simply rotate it until it drops out. It make require some pressure.