What do I do if my computer isn't holding it's charge?

Worst case your battery is worn out and you need a new one to restore longer usage on battery. I would first check the windows task manager and make sure that you do not have a process with high CPU usage(this will drain the battery quickly). Also closing background tasks can help reduce CPU usage and increase battery life. General maintenance as well, such as defragmenting the hard drive can make the computer have to work less and use less power. If you let me know what version of windows you are running I could tell you how to remove startup programs and background tasks.