1. I added an object and named it 'chest'.
2. Under the features tab for that object, I ticked 'container'.
3. I clicked on the container tab for the chest and next to "container type" I chose limited container. I prefer the limited container for things like this because I think it makes the most sense.
4. I ticked the boxes for 'Can be open' and 'Can be closed' and left the other boxes blank.
5. I put a '3' under the 'maximum number of objects' and left the 'maximum volume of objects' as is (you probably won't need this at all).
6. Under the Locking section for the container, I made sure the 'Locked' box was ticked.
7. Next to the 'Key' box, I selected the key that I wanted to use that would unlock the box. It will show up as long as you have created an object key that you plan on using on the locked chest.
8. There is a section under that saying "If the player tries to unlock/lock, but does not have they key(s), print:"
9. I typed in "This chest is locked. You do not currently own a key that fits the lock." You put whatever you want of course.
10. I also added appropriate messages in the print message boxes next to 'unlock message' and 'lock message'.
Good luck and Happy Gaming!
XanMag
If you want to download it and see it in the editor, it is attached below. Just ignore all the other gibberish in there! =)
The key is in room C.