To get more members for your PMC, other members have to apply for membership with you and your PMC. They just have to visit the profile page of your PMC and click on the button “apply” to send you their request.
A little red digit will tell you, if another player has applied for membership with your PMC. You then simply open your PMC and click on the pen next to the players name to accept or decline membership. Via this pen you will also be able to change the status of a PMC member after he or she has joined the club.
To get new members, simply write them a personal message and advertise for your company, so that they apply for membership with you or use the chat to ask players to join.