Set dancing is social dancing for adults to traditional Irish music done purely for fun, so if you are sociable, adult, like dancing to music and having fun then you're good to go. (You don't have to be Irish or traditional to do it).
Set Dancing is not Riverdance. Riverdance is based on Irish step dancing, which is largely a solo discipline done for competitive or display purposes. Set Dancing is nothing like that; it is social dancing done purely for fun. Bill Lynch's article The Joy of Sets describes it well and his website sets.ie is an essential reference for the subject.website: www.oxfordirishsetdancing.club