How to find a local computer's IP?

My mom's been having problems with her computer, and I want to get into her system from a remote access point, because it's not loading for her at all. The trouble is, I don't know how to find her IP, and she doesn't either....(I'm the most computer-literate in my family...) Anyway, I know you can find a webpage's IP address by PINGing it, but I don't know how to find just one computer's IP. Any help?