Goto civics advisor and pick one out of the column, and you can have up to 5 going at once since theres 5 columns...
You actually have 5 going all at once since the start of game, just that the first 5 don't do anything... They'll eventually cost you money though, so even if you don't want the effects, things like Free Speech is free during late game... Instead of "low maintenence" for the defaults...