As KirkFat said, What exactly are you trying to do? There are so many ways to do this. Sliding Door, Triggers, Console interaction.... ETC ETC..... Please if you ask a Question, give more detail. Don't make those of us trying to help, work for the information nessecary to give advice.
I'm kind of guessing, but you may be having a problem with map transitions. Any door from the inventory is interactable, if the mission involves interacting with the door. Perhaps you're asking how to use it to transition to the next map?
I'm sorry, I see that I was unclear earlier. I guess it is easyer to be specific when you are more familiar with the foundry, which I am not.
You are right Kirkfat. I want transition to the next map using one of the doors that is already in the premade interiormap. I am able to make a transition to the next map using a different object, but unable to select one of the preexisting doors in the map, for the same task.
Thank you for giving attention to my message even tho it was so cryptic.