First of all, this is the changeable holiday, sometimes it's celebrated in March,sometimes in April but this year it is celebrated on 5 may. for some other people it was celebrated on 31 march and it was called "western".
this time the patriarch goes in the grave of our Jesus (which is in Jerusalem) and when he comes out from the Grave he has the miraculous fire,which doesn't even burn anything for a few minutes.
If that all happens alright... if the patriarch has the Fire with him when he comes out from the grave then it's ment that the Jesus gifted us the life once again and he's with us. We call that the Jesus RAISED!