yes.. move the controle points.. just like other things. It puts it on the ground in the perspective view.. or like in the midle of the air only in X when you make one in the side view..

just seclect to view the CV's like you would the vertix on a poly. thin move them whare you want with the move tool. You can select all of it to get it in the ruff place you want thin tweek from there..

keep inmind when you extrude the circle along the path, the more CV's you have in the corners the smother it will make the bends.. don't put to many points.. but keep it in mind.. like its not a good ide to try to make a sharp 180 tern with only 3 points if you plan to extrued.. the tube will end up looking pinched.