Here is a quick step-by-step to help you through this installation step.
First, secure the vent sliders to the glazing bars that should already be in place.
After that, install the glazing bar that will be below the vent.
Then, install the vent frame bottom utilizing 1/4" x 1/2" bolts and nuts. The Vent slider should rest directly on top of the Vent Frame bottom.
Next, install the header using 1/4" x 3/4" bolts and nuts. The header should rest directly on top of the vent sliders.
After that, install the glazing bar above the side vent.
Attach one end plate using #8 x 3/4" or #8 x 5/8" panhead screws.
Slide the assembled vent into the header.
Attach the second end plate utilizing the same method as the first.