Lay the windshield flat, brush on the primer to the frame, then clean glass.
By the time your done cleaning the primer will be dry.
Cut a v-notch in the tip of the urethane tube, lay a bead around the entire perimeter about 1/4" wide by 1/2" high,(on the frame, not the glass) then have a helper help you set the glass in place.
After its set in place go around the glass and push on it to make sure there is good contact.