my first bike needs help. questions

dabac

You have the front half of a full suspension MTB. It's probably an entry-level bike, judging by Schwinn's current production. It has an aheadset fork, which is good, but it has a v-brake, which is bad - indicates either low-end and/or old stuff.
You could try contacting someone at www.schwinnbike.com and see if they can help you out. But I suspect that tracking down a new rear might turn out tricky and expensive. Really makes me wonder where it went.

Unless you strike it really lucky I think your best option would be to hang on to it as donor parts. Pick up another bike cheaply with some of the bits that you've got broken, do some easy transplanting and you've got yourselves a beater/entry level bike at a bargain price.

Or break it up and sell it as parts. There's a steady request for cheap spares for beaters or bikes that have to be left in theft-prone areas. Won't make you rich but it should buy you a pizza or two...