The more points you have, the more your vote counts towards the thing you want on a game design vote. 

To obtain points, you need to obtain badges. (Go to Profile -> Badges to see what those badges are). Badges are earned from participating on G2G, owning amplitude games and earning achievements, and joining things like OpenDev. Contrary to popular belief, badges like moderator, VIP, developer, and admin do not (currently) provide any points.

In order to obtain badges that require achievements to be completed, you need to sync your steam account (if you hit the gift icon at the top, there will be a screen to do it there). Each time you earn a badge you want to get points for, you need to resync your account.