The ejector basin should have 3 penetrations besides the inlet which is already connected in yr config: a vent hole, a discharge hole, and a hole for power cords. The teeny hole on top appears to be the pump power cord hole. I would guess the top hole is the discharge and the A-hole (HAHA) is the vent. If they supplied you with a pump, then a peek inside the basin should make it clear.
The question I have is where are the vents for the fixtures? I saw another post last nite by a guy with a similar config.