I asked for explicit instructions. You haven't given me much to go on.
There isn't an specific backup tool for Opera so instructions would depend on the one you had chosen and most probably you would find better help on the backup tool's forum/support.
Opera's profile folder
Check "About Opera" for the path
Do you mean I should use windows backup?
Well, that is a possibility. Or you can do a manual one.
How do I "inform Opera's profile folder"
Just select it when choosing what to backup.