Backing up data after a sibling link error

Apparently there is a sibling link error on my primary mac os hdd which is preventing me from booting into the mac os. I tried doing disk repairs that didn't work. I got a message when trying to do the repairs to back up my data and reinstall the os.

My question is: how do I back up my data?

Which version of OS X are you using? Time Machine is free and comes with Leopard and Snow Leopard. If you have Time Machine, the backup is made onto an external drive. If you're using a version of OS X previous to Leopard you can use something like SuperDuper or Carbon Copy Cloner to backup to an external hard drive.

Regards.

I'm using 10.6.2. My initial thoughts were to use time machine to back it up but I'm not sure how to get to it. Like I said before, I can't boot into os x because of this error. Is there a way run time machine from the startup disk?