I have a schwinn ranger 24" with a tourneyTX derailleur, what options/alternatives do I have to change the rear derailleur? I am not sure what derailleur options I have available to me here. I don't know the specifics are to get a rear derailleur that fits this bike. I am not too familiar with bikes or what parts I can and cannot use. I couldn't for instance, go to the a department store and pick the first rear derailleur I see off the shelf, right? It would have to be the right specs. My question is what are the correct specs for this bike to find an alternative rear derailleur? The current one I have has broken gears. Aside from that the rest of the bike is in overall good condition, just need a new derailleur.

Thank you
The easiest thing to do of course is simply take it to a bike shop. You'll get the correct part and the gears set up and adjusted properly.

If you want to obtain a replacement yourself, you can order a replacement Tourney TX from an online bike components store, however, there are several variations of Tourney derailleurs available you need to take account of.

Schwinn does not seem to list any info for the Ranger 24" model but looking at some online retailers that are offering it, it's a 7 speed, uses a direct derailleur mount and seems to have a medium cage length.

Target.com lists a Ranger 24" here: https://www.target.com/p/schwinn-boys-ranger-24-mountain-bike-black-red/-/A-50676983. That bike seems to have a Tourney TX35D model derailleur.

You'll want to check that the bike at Target looks like yours as it may not be the exactly same as what you have. 

Niagara Cycle has a good selection of Tourney TX  derailleurs available (and TY, which appears to be a slight upgrade). You should be able to find something that matches the mount style (hanger or direct), number of speeds (I'm fairly sure all Tourneys are 6 or 7 speeds) and cage length that you need. If you are not in the UK, Canada or Australia you should be able to find the correct model on Amazon.com or another online retailer.