syncing macbook pro to imac oldie

Hi, I'm computer illiterate so be patient. Yesterday I purchased a iphone 4 and pluged it in to my imac to find the software not compatible. After reading a bit I just purchased a macbook pro. I'm trying to retrieve all my contacts pics and music off my old imac and will continue to use it at home. The imac does not have a square type firewire plug in the back, it has a D shaped one... How do I link them up to share all my info... simply? Please help in LAME terms.