How to set caster?

I'm just reading up a bit about DIY alignments and I'm wondering how to adjust the caster. From research I found it is best to get as much positive caster as possible usually somewhere around +2 - +4 degrees. But how do you set this..?

I found an image that Autoxcuda posted but i'm not sure I get what he means with "cam adjuster all in and cam adjuster all out"?

can someone enlighten me LOL