How to use autotiles for rooms?

[Midnight Daydream]

I, being super smart and all, don't understand how to add a border to the top of a room. I don't get how to use the autotile I think you're supposed to use.

I don't really know how to explain this, so I hope someone understands what I'm trying to say. ^^;

 

[Tindy]

Take the roof autotile (the one that looks like a chimney) and use Fill on layer one (the screen should now be black). Add floor and wall tiles on layer one.

 

[Midnight Daydream]

thank you so much!! :D