The side of your Eheim pump with the word Eheim on it is the outflow of your pump. Everything coming from that side has pressure on it. The clear tube attached to that side is your outflow. That valve on it should be wide open, or just removed so it doesn't confuse things. It is only useful it if you want to shut the whole thing off to move your reactor for cleaning or reloading.
The flow control valve goes on the side that the Eheim pump is sucking in from. You have a black tube attached to it in the photo. The side with the silvery colored strainer basket on. This is also the side where the co2 is coming in. The black tube should be coming from your tank, through a flow control valve and then attached just like it is to your reactor. The valve on this black line is the only one you use to adjust water flow to and from the reactor.
In other words, the intake side has 2 hook ups, the co2 coming in, as well as the tank water coming in. It has some suctioning it. The out flow side only has one hook up. It puts out a little pressure and it goes back to your tank.
The single hose port in the top of your lid (right next to your pH probe) is just an air release to help you keep from building up too much co2 in the chamber when you are getting things adjusted. Keep the valve on it turned off. That line does not need to go anywhere. If you get a bunch of co2 build up at the top of the reactor and want to vent it off, that is what the line is for. That is when you can open that valve for a second to let the gas out.
Some times I too wordy and not clear so one more time with this. No valve on water flowing out. You have one on there now and for now and it is partly closed. Open it all the way and leave it open, or just take it off the line so that it doesn't mess with you. Water needs to free flow out of the reactor. This will keep pressure from building up inside. This will also allow your co2 to come in freely.
Control the flow by controlling the water flowing in. Put the flow control valve on the black line. It should be coming from the tank. You have it in the correct port. There is suction on this side of the pump. Tank water and co2 both get sucked into the Eheim, they get mixed together and pushed into your reactor.
Fire it up. Open your in and out valves. Make sure the water flowing out can just drain out freely back to the tank. Set your co2 at about 1 per second and see if it keeps working. You should still have water flowing from the tank to the reactor and back to the tank and the bubble should be able to stay constant. 20 lbs on the co2 should be fine. If you have to go higher than that there is probably something wrong.
Now if all is good, adjust the valve on the black line. While you are adjusting that valve, you will watch the out flow line (the free flowing clear one) until it stabilizes at a drip rate you like. If that doesn't get you going then we can dig a little deeper.
