I don't know if it's because I'm used to 2000/2003 so much back then, but I don't see any option to use the select like in those two on RPG Maker VX Ace, and cut whatever you select on the map. Which is something I use to used to make it look like a rug reached behind the wall, and not make it look like it's at the same level as the top wall. I do not know how to do it on this Maker though.

One of the sample maps, like the "Library" shows it can be done. Can someone help me out because it's bugging me.

Try holding shift down when placing the rug 'block' down next to the wall you want to have it go behind. This will change the rug 'block' placed to a central rug block piece. Then redraw the blocks around the outside of the rug to make the rug update to have an edge. Do not redraw the wall.
So in the picture i included I tried to illustrate that you have to draw the rug holding shift and then add or redraw the blocks surrounding the rug.

Ah! Thank you so much! That itchy bug that was poking me is gone, Never thought Shift. lol