Thanks for the reply, TampaRaleigh!
I guess my main question is how to fit all the parts together, as in how to make sure they're all compatible. I was looking up various parts online and they all had so many numbers in the descriptions, I wasn't sure what to look for to make sure they'd work together. Also, do the parts only fit certain frame sizes, or will they all work as long as the cassette/derailleur/crankset are compatible together?
Sorry, I'm pretty new to the mechanics of biking haha.