Dell Inspiron 1370

I have a Dell Inspiron 1370 and it's working just fine. But I recently got a mail about backup files going to be deleted tomorrow, and I do not know what files they are talking about, whether they are important or not... In addition to this, the computer backs up files without me asking and keeps taking up more space in my C-drive - now I have nearly no space left and I can not seem to delete anything big enough to clear it up... Need some help!