Really, you guys are just completely horrible. I understand that people are mean on here, but he's only asking a question that he doesn't know.
Anyway, since it has been answered anyway, I suggest you play the tutorial. It has a little bit where you have to use the Printer on print bricks. So, that explains placing them on, and to get the actual bricks, they are in your Brick Menu, under 'Bricks', 'Plates' & 'Ramps'. The very bottom bricks in the menu's, they will be the print bricks. Simply add them to your brick selection, and then plant them. Follow on from what the tutorial showed you.
