I need help scripting a group rank only door?

If you could help me here I would be very pleased. Ok so the group only door I want it to where if you are not in the group it grabs a gui that says Access Denied (you can make the gui name putguinamehere1) And I also want it to where if you are inside the group it gives you a gui that says Access Granted Officer (Name that one putguinamehere2)

Thank you for reading and taking your time all users.