Bascially what you will do is get off the airplane and go get your bag and clear customs. As soon as you walk out of customs there is an AC
(other airlines too) transfer desk - you can give them your bags (if required) and check in for your next flight. From there, you walk out into the international arrival hall, go up some moving stairs. Go down past the international check in - through the new link terminal and you arrive at the C security line up. If you go through this line - you can still walk over to the B gates by use of a Moving Walkway.
Hope I am usefull its kind of tired and I just threw the information at you, but that is the just of it! If you have time - walk around a bit YVR
really is a nice airport.