What is an upgrade for a phone & Jailbreak?

[Aaron610]

what is a upgrade for your phone i have an iPhone 3g but i want to know if you upgrade your phone do you stay with your phone or do you have to give back to the company and if i jailbreak my iPhone what does it do to my contract i know it is legal now but I'm saying does it lose my warranty and i don't know how to ask my games up on iTunes i know how to sync them to my computer but i recently bought 5 games and don't know how to sync them on i feel like I'm going to delete all my games on accident because i don't know how to put it on my computer i don't know what revert is neither so please help me