connecting to iTunes

I know this is probably a really dumb question to most but this is my first iPhone and i have no idea what i am doing. I have the new 4s but Verizon is sending me a brand new one due to the fact that the camera on mine is malfunctioning. I need to hook the current 4s i have to my itunes to back up my data. will it save all my applications? and how exactly do i know if everything backed up properly before i give my phone away? thanks for your help i just have no idea what i am doing!