Need Auto Backup software asap

I need a software that can back-up my files to the computer once I insert a flash disk. I mean, I have documents that I save on a flash disk and I want an auto back up every time I insert my flash drive in to my computer. I do not want to do it manually since I forget at times. If there is any or a list of software please inform me and how it functions. If it is free, it will be better.
