Before you can learn how to apply drywall tape, you need to determine which kind you want to use. There are two types of tape that are commonly used for drywall repairs, one is made from paper, the other is made from fiberglass mesh.
Using Paper Drywall Tape
Installing drywall tape with paper tape will require one extra step. First you have to apply mud and wipe the tape down to get it to stick to the drywall. Spread about and eighth of an inch of compound along two opposite sides of the seam or joint.
Cut a piece of paper tape about two or three inches longer than the joint you are taping. Center the tape over the joint. Use a four or a six inch knife to wipe the tape down, pressing the excess mud out from under it. The tape should be fairly tight to the wall. The flatter the better.
Repeat this for the other seams or joints you are working on. Where joints intersect, make sure the tape laps onto the other pieces of tape by at least an inch. Also you need to make sure that there is mud between the layers of tape. Wipe out the excess mud and then walk away. I will repeat that 'WALK AWAY', you have to let it dry.
Do not attempt to coat the joint with compound over wet tape. You will be very angry in a hurry. Find something else to do until the tape dries. Don't blame me, if you had spent the extra couple of dollars on the fiberglass tape, you would not be doing this step. Taping mudding drywall is all about drying time, mesh tape eliminates one drying phase.
To cut the tape hold it in the spot you want to cut it against the wall with a drywall knife. Hold tight and pull the tape, it should tear cleanly at the edge of the knife. Try it a couple of times for practice.
Installing drywall tape when using mesh tape is a little simpler. The mesh tape has some adhesive on it that allows it to stick to the wall. You cut the tape similar to paper tape. You do not have to apply mud to the tape prior to installing it. When you have the tape the way you want it, you coat over it with compound.
How To Install Fiberglass Tape
Fiberglass Mesh Tape sticks to the wall by itself and the holes allow the mud to bleed through and stick to the wall. You can put a first coat of mud on immediately. For taping mudding drywall repair projects this tape is the best.
For small jobs fiberglass tape is preferred, even though it costs more. It saves one step, thus saving time. The exception to this rule is taping inside corners. Fiberglass tape does a poor job in corners. You want to use paper tape instead. For about ten dollars, you can get a roll of each, should last you for a long time on home repair projects.
Fiberglass mesh tape has a self stick feature. You do not need to apply drywall compound to install the tape. Instead, you apply it to the wall at the locations that you need it.