Besides rotation, you can also zoom in and out (make the block bigger or smaller), in the 3D graphics window click and hold-down the RIGHT mouse button and while still holding it down (i.e. dragging it) move it slowly up and down. Again you can reset your view with the Reset View button on the lower right. You can also use the left/right arrow keys to rotate left and right and the up/down arrow keys to zoom in and out (you may need to click into the 3D graphics window first for the arrow keys to work).