To tile the floor, first select the product you want to use from the catalogue shown in the Components Window on the left side of the screen.
Click on the tile you want to use and drag and drop it onto the floor.
Once the tile is on the floor, you can use the settings shown in the Property window, on the right side of the screen, to customize the starting point, grout and grout color:
You can also tile the floor from the 3D View by simply dragging and dropping the tile onto the floor.