Rating, voting or scoring (call it what you will) is a tricky subject at best in the computer world. There is no authoritative way of voting in a way that is completely fair to all. One can only hope that what is in place will work and that everyone is happy about it. Presently, each member or guest is invited to attribute a score simply from 1 to 20 points to all submitted pictures.
Person you know outside the community you propose to sign up.