ok, it not bad for a beginner's map, but :
the floor is sand, doesn't do (it's also for a worldmap not an interior).
On the left you have to use a ceiling tile, as well as all around, they're on the first layer, top rather right, normally dark color and represented on the template just by a square sample.
the plant is a tree, that's also for the worldmap, look at the second layer, there should be plants there.
same thing for the column, it's a worldmap thing, just take it out, and yes, try to fill the room more.