Most yacht clubs are eagerly seeking new members - especially ones who already own boats.
US Sailing had a big summit meeting in CA over the winter about how to boost memberships. If you are interested in racing, call around and check the web to see what clubs in your area offer in the way of racing schedules. Note that your post's title is misleading: a Hunter 260 is not a dinghy. Some clubs may host one-design dinghy fleets and have busy schedules for them, but not for bigger boats like yours. Some clubs may focus more on the handicap racing you would probably be doing. Some may do both, and some may have enough Hunter 260's in their fleets for you to race one-design too. If you speak with the Fleet Captain at a club that appeals to you, he or she may invite you to try racing with them as a guest. It is a good way for them to get to know you (with an eye to getting a new member) and a good way to see if you like and fit in with them. Our club routinely invites non-member boats to race with us on Wednesday nights and in our weekend events. It's one reason our roster is pretty full.