A lot of deadeye's platform tutorials should still be helpful to you, although I think it's time he updated them to work in the latest version of Construct .
Personally, most of the time I would create my rooms on a single layout.
If you have a visible screen size of say 640x480, and you want 100 rooms, that's only 10x10 640x480 screens in one layout.
Then you can either scroll along with the player, scroll to the next screen when you walk off the edge, or (and this is the one you'd want if you were entering doors) you would just update the camera position to the part of the layout that holds your next screen.
There's plenty of examples of these ideas around the forum.