None of this is exactly easy, as there's no documentation, but I just did this yesterday. I have a 5-step onboarding sequence. (I'm coming from MailChimp.)
You set up an autoresponder campaign for each stage of the sequence.
Campaigns--> Autoresponders-->Create New
Then it's a matter of setting it up.
I made one campaign that looked how I wanted it to, and then just copied/edited it a bunch of times. When you get to the Confirmation stage, you can set up things like "five days after subscribe". That's all fairly easy once you get used to the interface.
A thing that tripped me up for a while ("How in the hell do I add an image???") is that the construction blocks for text and images are in a collapsible tab on the right hand side of the screen. You can pull it out and put it away.
If you want to go back and edit a campaign that you just finished, you have to click the Pause button on the right, then you're allowed to go in and make changes.