backup and upgrade

im being asked to upgrade to 3.0. it suggests i backup everything before i do or risk losing everything. when i click on backup, it begins talking about phpadmin. at this point im stuck, cause i dont know how to get to phpadmin much less do anything with it. im not a coder. some stuff ive figured out just because im stubborn, but i dont want to lose what ive created content wise. i know i get emailed backups of something, but im sure its not all of my info. is there a way to ensure i dont lose my info? is it neccessary to upgrade to 3.0 and if i dont does that mean i can lose my content? i need options. thanks.