As far as I know, there is no way to password-protect an Access table. What you need to do is setup user-level security for your database. With this method, you can control which objects certain classes of users would be able to access. Go to Tools/Security and try playing with User-Level Security Wizard.
Much simpler but less secure solution is to hide your UserLogin table. You can do so by highlighting your table, right clicking, going to properties, and checking off Hidden attribute. Once you do this, your table will disappear from the objects window. To temporarily display it, go to Tools/Options/View tab and check-off "hidden objects". Once you're done with table modification reverse the procedure for showing hidden objects.
Hope this helps,
Dusan