If you purchased directly from Adobe, or took the time to register when you installed, you can get your serial number from your Adobe account.
Also when you say in the program to backup where does it backup to
By default the dated folder and backup *.lrcat file it contains are written to the same location that is also the default for the catalog and previews C:/..../Pictures/Lightroom. Obviously having the active catalog file and its backup at the same location is no real backup, a C drive crash will take out both of them. In the backup dialog box in which you confirm the backup, you can browse to a better location.
how do i contact Adobe? i already wait for 1 uur on the phone, and i do not find an active email address.
There is no phone support for the standalone version of Lr, and you ask them, they will direct you here, so you are already dealing with the best people available to you.
You did register your copy, didn't you?