Entering MIDI controller steps in the Piano Roll Editor
I think it would be cool for the glissando to crescendo. We can do this in the Piano Roll editor with velocities.
Creating a crescendo by MIDI velocity
Press the Automation button to the left of the MIDI in button or press A. By default, unless you have been editing another MIDI Continuous Controller (CC), it will show the velocities of the notes.
If you hold the mouse down in the bottom of the editor just before the first note in the glissando and drag up diagonally to the velocity of the chord, you will create a crescendo:
To raise or lower them after the fact, select the notes in the Piano Roll, and use the Velocity slider.
Creating vibrato with modulation
The harp sound is not going to be affected much by vibrato, so let's use the Library to change it to a sound that will be. Open the Library by pressing Y, and navigate to Synthesizers | Classics...