You can announce through your Guild newsletter, post a note on the library bulletin board, or just word of mouth. Seems like you have planned well. I assume you plan to bring a iron to go with the ironing board and the library furnishes tables and chairs. Bring plenty of extension cords. Be sure to ask the library how much equipment can be plugged in before your overload the circuit. Hope you have as much fun at your meetings as we do at our monthly guild open sews that we have at our local library.