Follow these steps to create a new custom activity.
This feature is currently in beta, and will be made available to everyone during our Spring '16 Release. To get access to the beta, please contact your Sales Rep.
In Database Management click Custom Activities.
Click New Custom Activity.
Enter a name and optional description, then click Next. The API Name auto-fills, but can be customized.
Define your Filter and Trigger and click Next.
Give your primary field a name that summarizes what the custom activity is for.