The camshafts have slots at the end of the camshaft. To use the tool you have to remove the valve cover. The tool fits in the slots at the end of the camshafts and holds the camshafts in place. The crankshaft makes two complete turns for every one turn of the camshaft. If the tool does not fit you might need to turn the crankshaft one complete revolution. There are two Top Dead Centers (one is the exhaust stroke and one is the compression stroke).
I think the Crankshaft is supposed to be aligned at TDC of the compression stroke. When I changed my timing belt I used a thin piece of metal for a camshaft holding tool because I had the crankshaft aligned at TDC of the exhaust stroke.
