horizontal laying

[gürkan]

sa,Hello. I am building a small structure consisting of 6 rooms, which houses the dressing and referee rooms of an artificial turf. But my floor has to be horizontal, because the columns at the front of the building are 3.7 m, the columns in the middle are 3, and the columns behind are 2.61 m. I figured out how to throw the beams horizontally but I can't throw the tiles horizontally. Can you explain your method? thanks. Also idecad Turkish program?