The Disorder Campaign has five missions like the Order Campaign. Mission 1 is Orks only, missions 2-3 have predetermined Chaos Space Marine and Ork parts, and mission 4 is the same as Final Journey (you can switch between the Disorder factions this time). Mission 5 is decided by the winner of mission 4. In this campaign you regularly fight all the other factions, including the other Disorder faction – even when you're "allied" they are always red, not blue, so you either avoid them or fight.
The advice given for the Order Campaign goes here too – if you are not familiar with Chaos Space Marine and Ork technology and economy systems, you should play the tutorials for both factions before starting the campaign.