To drywall a ceiling by yourself, you need to follow these steps:

1. Inspect the ceiling for obstructions or problems that need to be fixed.
2. Find the ceiling joists and mark their location on the wall.
3. Mark the placement of light fixtures and vents on the drywall.
4. Smooth the rough edges of the drywall pieces.
5. Build a T-brace or use a lift to support the drywall while you attach it to the ceiling.
6. Measure and cut the drywall to fit the ceiling dimensions.
7. Start from one corner and screw the drywall to the joists, using a drill and drywall screws.
8. Repeat the process until the entire ceiling is covered.

Here is a detailed tutorial on how to install ceiling drywall with pictures. You can also check out this video tutorial on how to finish a drywall ceiling for beginners.