Inside house & outside house are 2 differend layouts. So, when some condition is met (usaly overlapping some sprite while a key is pressed) goto another layout. That is the easy explination.
But it brings some 'to do' & 'to watch for' things with it.
You need to learn the concept of 'global' objects & variables, decide if you go with 2 event sheets or just stay with 1, etc .........
And that al is largely coverd in the forums.
This should help you to get gooing.