If you didn't remove the distributor, then it is very simple. Turn the cam pulley, so the mark on it points at 12:00 (there is an indention on the top of that black plate that sits behind the cam pulley, to line the mark up with). Turn the crank, so that the mark (it is either a dot or a line) on the timing belt cog is at 12:00 and lines up with the arrow/pointer that is cast into the oil pump (the mark on the oil pump is just right above the timing belt cog, so it might be hard to see...might need a mirror and/or light, to make sure the marks line up). Once both the cam and crank marks are exactly at 12:00 and lined up with their respective alignment marks, put the timing belt on.