Decide where in the house you want to build your vocal booth. This will largely depend on where you will be building your whole home studio. The two most ideal places would be the basement or a spare bedroom.
Clear out the space you have chosen to use for your vocal booth. Remove everything but the carpet if there is any. If there is not any carpet, you may want to have some put down inside the booth once it is completed.
Use a measuring tape to measure the height of the room from the floor to the ceiling. You will need to know how long each of the wood support beams will need to be when constructing your walls.
Build your walls. Start by setting up the supporting beams and build a wall coming out from the wall. Decide on the size of the booth, and put up three more walls, one on the opposite side from the first wall you built, and one that will have a doorway cut into it to enter and exit the booth.
Hang your drywall over the wood beams you used to build the walls of your recording booth. Allow the drywall 24 hours to finish drying.
Use a saw to cut out a space in the one of the walls of the booth for a ventilation fan. The air flow and temperature will not be very comfortable in the booth, so you will need to install a ventilation fan to keep the air circulating.
Soundproof your vocal booth. Purchase some soundproof foam and hang several sheets on each of the walls including the door to the recording booth to help deaden the unwanted sound when you record.
Move your microphone into the booth and place it in one corner of the room. Cut a small hole through one of the walls closest to the microphone, and run all of the wires out through that hole to your other studio equipment.