how do you figure out 3/4 of a tablespoon in Party Pretzel Bites recipe?

Whenever you see a fraction of a tablespoon, just remember there are three teaspoons in every tablespoon and then you can convert to teaspoons.

I just answered my own question. Thanks!!

do I use the 1/4 spoon for the 1/4 part?

Good question -- it's 2 1/4 teaspoons.