To Promiselamb:thanks for your comments
would you be more explicit about your last comment ;do you know exactly where it back up on drive c:  ?I have lots of space and 3  hard drives

Yes when you install it. it will make its own folder called adobe lightroom. in there it will back up in folder i think called back up.

but my husband said on his computer it did the backup in documents/images.

maybe you can tell it where to backup when installing it. and we just didnt look when we did so.

and by the way that is a good book I have it :-)