On the Elements section, click the Add button to add the required elements to the project:
Click the toggle buttons on the the elements to enable them.
Open the Mapping section and select the desired MIDI Output functions. Start by selecting the MIDI Output element on the left list (functions). Select a desired output (Note On, Control Change, etc.) and tune the parameters.
Finally select the Keyboard on the right list (controls) and assign the previously selected MIDI Out function to one of the available controls.