How do I call a two blue line pass?

Rule 8.5: the ring may not be passed to a teammate directly from the defending zone to the attacking zone.

• If a teammate of the player who last contacted the ring in the defending zone controls the ring (before an opponent contacts or controls it) after it has travelled untouched, play is stopped immediately and a two blue line pass violation is called. The mechanics have the ring awarded to the other team as a free pass in its attacking zone.
• If that teammate only contacts the ring (before an opponent does), a delayed violation is signalled. No player from that team may contact or control the ring within five seconds from the time an opponent contacts or controls it, or before the ring completely leaves that zone. If that team gains control during the count, play is stopped.
• If an opponent contacts or controls the ring first, the violation is dropped.
• A player who is ineligible to play the ring because of a delayed violation and is the only player to touch the ring in the neutral zone does not stop the violation applying.
• Wash out: if the eligible team has had reasonable time to play the ring and it is now playable by either team, the on-ice official nullifies the potential violation with the wash out signal and verbalizes "play". The team that is eligible must still go to the ring without delay.

Source: Rule 8.5 and Annex B, mechanics 18 and 22.