As BMR shows in the illistration. The crank pulley has a timing mark that aligns to the mark on the oil pump. The camshaft pulley has a hole in it, you look through the hole to align it with a mark on the head.
That is TDC #1, and the point you want to install the belt. Make sure the tensioner is moved all the way to loose, slightly tighten it to keep it there and once the belt is installed loosen the bolt and tension the belt.
While you are at it (at this point) inspect the oil seal at the camshaft and at the oil pump for leaks, now is a good time to replace them if they are leaking.
Handle the timing belt carefully, no oil, grease or coolant should come in contact with the belt.