A tae kwon do uniform -- known in Korean as a dobok -- is, above all, a functional garment meant to allow freedom of movement and withstand the abuse of sparring and repeated, intense workouts. A tae kwon do uniform also indicates your rank, might indicate which school you train with, and can even contribute to the appearance of clean technique by emphasizing the snap at the end of a punch or kick. Wearing your tae kwon do uniform properly is also a sign of respect to both yourself and the teacher and other students around you.
Consult with your instructor before purchasing your first uniform. Some instructors allow you to purchase your own uniform, but many require you to purchase a uniform directly from them with the school's logo embroidered on the back. Tae kwon do uniforms are almost always white, and your first uniform will almost never have any extra coloring around the neckline, which is reserved for more advanced students.
Slip on the uniform pants over a pair of comfortable underwear. The pants are gusseted to allow free movement without binding in the crotch, but underwear is still a good idea both for hygiene and in case of an unexpected seam blowout. If you're sparring, you might want to consider wearing a groin protector -- they are required during tournaments and may be required or optional during in-class sparring. You can purchase groin protectors for both men and women.
Tie the drawstring waist of the pants so that they ride above your hip bones with no danger of slipping down. Low-rise tae kwon do pants do not exist. And despite wry comments to the contrary, the belt does little to hold your pants up; only the drawstring does so reliably.
Put on a sports bra -- required wear underneath your tae kwon do top if you're a woman. If you're a man, you could theoretically go bare chested, and in theory a woman wouldn't have to wear anything over her sports bra. But wearing an undershirt helps both genders cut down on how often you launder your uniform, and some instructors may require an undershirt as part of the uniform.
Pull the uniform top directly over your head, with the "V" of the neck facing forward. You might also encounter tie-on uniform tops that look a bit like a crossover sweater or tunic. For a tie-on top, slip both arms into the sleeves, then cross the right side of the uniform across your body. Use the cords on the uniform to tie this flap in place, then cross the other side across your body and, again, use the cords fixed to the uniform to tie it in place.
Locate the middle of your tae kwon do belt. Hold this against your belly button and wrap both ends of the belt around your back. They should layer flat, one inside the other, so that the two ends cross when you bring them around the front of your body again instead of crossing behind you.
Tuck the outermost belt end up through the other layers of belt in front of you so it emerges pointing up at your chin. Then cross the ends through half an overhand knot, as if you were getting ready to tie them like shoelaces. The belt should form a tidy knot, with both ends hanging straight down in front of you.