Communication is everything. Have a conversation around swinging and work your way up to it. Try a swinger club, they are a lot of fun. Set boundaries and make sure your wife knows it is not expected that she has to play. Sometimes getting into a swinger club and seeing how it all works and meeting some members is a great way to break the ice.
My wife was hooked after our first time. Now she loves the couples side and the single side in the playrooms.