Could you tell me how to align the timing marks on a 1999 trooper 3.5 liter?

The factory marks are incorrect, the best way before removing belt is marking with tink on pulleys and the guard behind them, or if too late, find some one who has a the same year, and just take the timing cover off and have a look, it not easy job to by yourself, have someone who has a bit of mechanicaly knowledge to give you hand to do it.