Welllllll... there are two sides to this. Most successful swingers are older (at least late 20's, IOHO) couples that have been in long term committed relationships. She is very young to be jumping into this pool, but the cat is out of the bag. First, time for a long talk about swinging in general as well as the emotional aspect involved with having multiple sexual partners. If she is still wanting to attend a swingers club after this, with her knowing that she will be, by far, the youngest person there and lots of people will be twice...thrice her age and naked, and as a young unicorn...she'll be fresh, young blood in the water full of hungry sharks. The question then becomes: do YOU want her to go to a club without you? At least you (one or both of you attending) will be able to provide some protection and supervision for her once the sharks begin circling. Just set the ground rules (like it is just a visit to see what it is like and that nobody is going to be playing that night) and let her see what does on behind the curtain instead of her imaging that a swingers club looks just like they do in porn (all young, perfect bodied people having fun). After that, if she is still interested...well, is it a surprise? The apple doesn't fall too far from the tree. While it will probably very uncomfortable and awkward at first, that she has come to you requesting your help is a very good thing. Help her enter into this with her eyes wide open and knowing that you have her back, and then it is up to her.