Instructions
Scroll through your inventory to select your desired building block.
Aim your cursor where you want to place your block. Right-click to place the block.
Repeat Step 2 to place your entire building. This can be any kind of building you want, large or small, of any shape. For example, you can keep placing blocks in a cube shape to make a standard house, or you could place them in a pyramid for a statue.
Scroll through your inventory to select a tool. The tool you want depends on the type of block beneath your building. For example, if you have dirt, sand or gravel beneath your building, select the shovel. For stone, select a pickaxe.
Hold the left mouse button down to remove a block. Remove all of the blocks beneath the building. The building will stay in place and float over the hole you make.