Can't Access Time Machine Backup Files After Reinstall

I just completed a clean reinstall of Mountain Lion. Obviously I've missed some important step(s). When I enter Time Machine, I can see that there are older back ups by the dates on the right hand side of the screen, but they are greyed out. I'm confident the files are there, the issue is being able to access the files.

I've seen some notes about "reassociating Time Machine" with my "new" computer with some terminal commands, but I get lost with the instructions I've read and it sounds like if I do it wrong there is a pretty good chance I could really cause some damage. For the time being, I've turned off TM, but the dirve is still mounted and available.

For some reason, I was able to access and resotre my Documents folder - I just can't get into all the folders/files. Prior to the reinstall, I did visually confirm that I could see and access all my backup files.

Any help is appreciated.

Thanks.