Backup Disk full and no media sets

Hello:

I'm setting up a new BE 2012 server with a disk backup.  I've set the backup job properties to Keep for 1 hour.  Despite that the disk has filled up and backups no longer run because of the full disk. 
I'm thinking Media sets are the way to get backupexec to purge space on this disk as needed but there are no Media Sets.  On the other backupexec 2012 server I manage under the Storage tab there are Media sets I'm able to assign storage to. On this problem server there are no Media Sets.  How can I create Media sets with backupexec 2012.  This used to be easy to do with previous version of backupexec but it seems to be hidden somewhere in 2012.

Tx

Bill