We went to the state fair (held in the state capital) for the first time this year.
For my birthday, my parents got me tickets to Hamilton (my favorite musical!).
Explanation:
Parentheses are used to add some extra information, such as a comment, an example, or a short explanation. It allows a writer to give us additional information, but this information is not very important for the sentence idea; the sentence will still make sense and have a complete thought even if we omit everything that is inclosed in parentheses.
We don't put any punctuation mark before parentheses and put a comma after the closing parenthesis only if the sentence needs a comma (or a point) anyway.
Only in these 2 sentences, we see the correct use of parentheses:
We went to the state fair (held in the state capital) for the first time this year. - This sentence will still have a complete thought without info in parentheses, the information is not very important: We went to the state fair for the first time this year.
For my birthday, my parents got me tickets to Hamilton (my favorite musical!). - The info in parentheses here are not very important also, we will understand the needed information even without it: For my birthday, my parents got me tickets to Hamilton.
As for other sentences that use parentheses wrongly:
My sister has homework for three classes tonight (math, English, and biology). - there shouldn't be parentheses, this sentence has a list of classes, it is needed information. The correct way to write this sentence - My sister has homework for three classes tonight: math, English, and biology.
The student body voted to select (the person) who would get the Best Teacher award. - The information in parentheses here is very important for a sentence, without it there won't be a complete thought. That's why the correct way to write it - The student body voted to select the person who would get the Best Teacher award.
(When he made the hot chocolate) my brother left out the most important ingredient. - There is a wrong way to use parentheses, we shouldn't omit the dependent clause of a sentence, it will lose its main idea. The correct way to write this sentence - When he made the hot chocolate my brother left out the most important ingredient.
I hope it helped you :)
