user associated with one monitor group

You can associate one user to one Monitor group. For this
1. Create users from Admin Tab ->User Administration and then add users.
2. Go to Home tab and then click on the Monitor Group for which you want to associate the user.
3. In the Monitor Group page, on the left side you will be able to view an Edit link.Click on the link and you will be able to view all the created users. Associate the user you wanted to monitor the selected Monitor group and click on Save.

After you logout and login as the new user, you will be able to find only those monitors present in that group.