Hi Donald.
The tube straight out the bottom is the overflow. Cap it after filling the tank.
The bent tube out the top closest to the wedge is the line to the engine, or pick-up tube.
The bent tube out the top closer to the flat side of the tank is the uni-flow vent. Also used to fill the tank. Leave it open to the airflow.
Mount the tank with the center of the wedge on line with the needle valve assembly, ( or center of the venturi for profile mounted engines) but be prepaired to adjust it up or down a little for even upright/inverted engine run. If the engine runs richer upright, lower the tank and vice versa.