Maximum PC

Hello, my sister has moved away to a different state and I wanted to set up a way for me to get on her computer through mine to help her with her computer needs. We tried to set up a remote desktop connection but it wouldn't allow me to connect despite turning on remote desktop on both computers. I used her IP adress to find her computer but no luck.
I was wondering if first we need to set up some kind of network or even if it's possible to do what I want to do.

Any assistance would be great. Thank You.

you may want to try Team Viewer http://www.teamviewer.com/en/index.aspx

its fairly easy to setup and use

You don't want remote desktop, what you want to use is called "remote windows assistance."

Typically the issue with home (or business) setup is that you are both behind "network address translation" routers, that "change" what IP address you are on, and don't usually allow someone from "outside the home network" to get directly to the other computer. But no worries, as mentioned before, the "Team Viewer" products works great, and is free (for non commercial use). I love it.
Also, DropBox makes for a super easy way to share files between you and someone you trust. (I'll just put my referrer link right here: http://db.tt/D5BQcbf )