just line all the white ticks up with their counterparts on the cam gears and the crank. Put the belt on and make sure all the ticks are still lined up. Tighten up the tensioner and make sure all the tifcks are still lined up. To do this you might want to set the crank one tooth off so that when the tensioner is tightened it will turn it into time. If all the white marks line up when you're done then its good. Turn the crank a few rotations to make sure that its good and everything still lines up. Then you can pull the pin on the tensioner. If you can re-insert the pin then its correctly tensioned. If you can't then you didnt tighten it up enough and need to re-compress the tensioner and do the whole process over again.