When you run Backup for Workgroups, the Backup panel is the opening window. You can perform a backup at any time by pressing the Backup Now button which appears on the Backup panel. If you have multiple backup sets, you will need to select the name of the Backup Set that you would like to run. If you have just one backup set, that backup set will run immediately.
If you would like to modify any of your backup sets, create a new backup set, or delete an existing backup set, go to Tools > Manage Backup Sets Wizard.