Ok the combination is really simple but i forgot so i cant tell you but i can tell you how to get it.First look at the tapestry in the room, you see the colors on it.There are shields in the room with those colors on it and pictures on them.Use the colors on the tapestry from first to last,match them with the shield and use the picture on that shield in the order on the tapestry.This might sound hard but it is really easy.
There is a really helpful walkthrough on Wizard101 Central. I spent almost half an hour trying to figure this out, and got in first try after reading the walkthrough. Follow the instructions exactly. Hope it helps!