Drywalling a ceiling is one of the most physically challenging projects. The sheets of drywall have to be held up and in place long enough to allow you to screw them into the ceiling joists, which is difficult with two people and impossible with one -- unless you have a drywall lift. Rent a metal lift that hydraulically raises the drywall to the ceiling and holds it there, but if you've just got a few sheets to hang, save the money and build the lift yourself.
Use your tape measure to measure the height of the ceiling, from the floor to the ceiling joists. Take the number you come up with and subtract 1 1/2 inches (for the thickness of a 2-by-4), then subtract the thickness of the drywall (generally, 1/2 inch). Cut your long 2-by-4 at that length on your mitre saw.
Lay your long 2-by-4 on the floor on its narrow edge. Lay the 3-foot 2-by-4 at one end, on edge, perpendicular to the longer piece. Drive 2-inch screws through the face of the shorter 2-by-4, into the end of the longer one, so it forms a T.
Set the piece of drywall on end against the wall, under the ceiling area where it will go, with the finish side facing out. Set the short piece of your drywall lift against the drywall. Use your screw gun to sink four to six 1 3/4-inch screws through the 3-foot 2-by-4 and into the drywall. The screws shouldn't go all the way through. Let the end of the long 2-by-4 rest on the floor.
Carefully lift your drywall sheet toward the ceiling. Initially lift it by the edges, letting the attached 2-by-4 apparatus just hang from it. But once you've got the sheet near the ceiling, grab the long 2-by-4 (which will be nearly vertical by now) and jam it between the ceiling and the floor, guiding the sheet into place. Once it's where it belongs and the drywall lift is holding it up, bring in your ladder, climb up, and sink drywall screws through the drywall and into the joists. Once the piece is secure, unscrew the drywall lift and remove it.
Wear goggles while using your screwgun.