How to participate in crusade?

[superdeluxe]

So the pope calls for crusade for Israel , any ways I get to the caliphates land and I'm not seigeing anything, is there anything special that I need to do ? I was in some of the defenders lands

[XxIzualxX]

You need to join the war by clicking the Crusader's Flag in the top left under your character's portrait and then click the join war button on the menu that pops up. After some days the Pope will accept your offer to join the war and then you can begin Crusading.