Volvo: Timing belt change

Question
While I was taking off the crankshaft bolt, The timing belt bolt and the crankshaft pully turned. What do I need to do to set the timing back.

Answer
you didn't mention what vehicle but if you look at the crankshaft gear there will be a raised piece on it ,it lines up with the mark  on the front cover you should be able to find a pic on line if you give me the model i will attach one with the necassary information ..