We advertised on FB in the local plant, gardening, seed, homesteading and prepper groups. There were ads at local Farmer's Markets and in local newspapers that gave free ads for community events. We established a meet-up group and informed all the local urban and rural farms that deal with the public.
This workshop was about learning to propagate figs. I gave them an introduction to soil including how to maintain air spaces then talked about figs and told them about the numerous methods to root them. Then I showed them what I believe is the simplest method for beginners - Jon's U-Line bag method. I supplied the large perlite and everything else, showed them how to rinse it and why, etc. They each took home cuttings and instructions on how to care for them, pot them up and over-winter.
This was our second event. The first one was last summer on how to grow figs because this nursery has fig trees from California from the 1940s that they've been selling. There were several people who weren't at the first one so we went over the basics of up potting and future care. There will probably be a repeat of the first one in mid summer. They can all contact me with questions and several have.