Go to your favorite search engine, type in "BDSM munch <your nearest larger city and state>". You should find what you need.

Munches are usually easily found. In some areas, a request for invitation must be sent and the new person will attend as someone's guest. You don't have to 'know' someone.

In my area (the Twin Cities) there are at least 2 munches per week and no need to be invited to attend most of them.

Etiquette - street clothes, don't get drunk and make an ass out of yourself, be polite and kind, just as you would be in large group of people you don't know.