To create or edit a ladder, go to the "Ladders" section of the "Start Organizing" menu at the top of the page. Next, choose a group you want to add a ladder for. If you want to make a new ladder, click the "Add New Ladder" button to get started adding a new ladder. Otherwise, click the manage button next to a ladder you want to edit, then the edit button on the next page to edit that ladder.
On the editing page you can give you ladder a title (this is for your internal use only) as well as write internal notes about the ladder, explaining to your colleagues what this ladder does. Below, you can click to start creating new rungs, triggers, and steps and build your ladder.
In the toolbox on the bottom, if your ladder is not published yet you can save your ladder as a draft of publish it, and if it has been published already you can save your changes.
See here for more information on the components of a ladder -- rungs, triggers, and action, decision, and wait steps.