How matches are arranged in taekwondo?

It depends upon the tourney. Most have belt range, age, and gender-based divisions. For example, black belt, over forty, male. Some smaller contests have less divisions.

The ones I attend match up the first rounds in order of apllication submittal time. First one to turn in paid application papers gets to go last. It gives you a chance to stretch and observe the competition.

Leo L is right. And nowadays, it is common to see tournaments separating competitors by the number of years they practice in a martial art, and no by the color of their belt. Thus, someone who practices for Karate for 20 years and then joins a TKD school as a white belt shouldn't compete as a white belt: he should be competing as someone who has been training for 20 years. Therefore, it's not uncommon to see white belts sparring black belts for this very reason.

With less formal tournaments, classifications for children are more strict: first by sex, then by experience, then by age/height/weight. It is thus possible for a 10year old to spar a 14 year old if they are of the same experience, height, and weight. Conversely, two 14 year olds may not compete together if they are of significantly different height or weight. And for adults, they tend to separate by age - usually, adults = 16-40, and seniors are 40+ for example.

For formal tournaments, it is by sex, then experience, then weight.

They're basically arranged the same way that Pakistani marriages are arranged. The parents of the challenger will invite the champion's parents over to dinner. After making small talk, the challenger's parents will make a dowry offer usually in the range of 4-6 goats. If things go well, the match proceeds and the goats change hands.