Recently, I got a Seagate Backup Plus 3 TB external hard drive so I could back up my files for when I would bootcamp windows 7. When I plugged it in, the window asking if I wanted to use the drive as a Time Machine backup popped up, but instead I clicked on "Decide Later." I later realized that I wanted to set it up, but I cannot figure out how. If I try to set up Time Machine in system preferences, the list of backup disks is empty. My only other option is to backup everything manually, but the time and human error involved would be unavoidable. I use 10.6.8.