Basic idea is that you have a deadline to pass all the agendas in a row (i.e. first row in the first year, etc.) with the deadline represented as a national spirit. When you start a focus corresponding to an agenda, that agenda will appear in the Agenda GUI.

You can invest political power by hitting the button near the top of the selected agenda. Having a high amount of pp invested increases the chances of success and the degree of success. You'll receive events that add pp either for or against the bill. Riders will also appear that give some penalties upon the conclusion of the agenda and must be averted by paying political power.

Ignoring the agendas until the deadline passes results in them being abandoned, resulting in a different bad modifier than if the agenda was proposed but failed really badly.

(basically, click the pp invest button till it's like 150-200, remove riders you don't like, and make sure you don't miss the yearly deadline)

I got it now! Unfortunately I wasn't able to get any events that would get me more than 50 investment. All of them ended in a stalemate. At least I'm past it now!