Jobs are a series of tasks that can be performed against a singe data source. Each Jobs may contain different Stages, which allow you to move the data to different destinations. You may have an unlimited number of Stages per Job, and an unlimited number of Jobs per Bindings File.
On the projects tab, click on the name of the project you created. Now inside your project space you can create new jobs by selecting the plus sign (new) icon on the right. Enter a meaningful name for the new job. This will create a new, blank definition for the database connections and mappings.