broken hose on back of my merc (what is it?)

[mallardtone-man]

I recently bought this Mercury outboard its a 1999 120 horse when I took off the cover there was a small white plastic hose broken off coming from the top of the motor from a valve at the top of the power head I assumed it was a breather or something because there is another Black heavy high pressure hose that goes to the outlet on other side of the block (left side if you are facing the back of the motor. I have run the motor hooked up to water (only for about 5 mins) and water comes shooting hard out the valve on the top and I didn't see any coming out of the outlet on the bottom right side of the case that the black High pressure hose is attached to. I assume that I need to attach a hose to this top sales and run it to some kind of outlet or out of the motor somehow what I need to know is where it should connect to and if it sounds like the motor is functioning properly I thought the water should be coming out of the outlet on the bottom right side of the case also I am a little confused as to why the original piece of hose left on the valve on top was so small it was like fish tank hosing does not seem appropriate for high pressure water please help me on this guys I am supposed to be running this boat on Saturday and need to get it figured out I have attached a couple of pictures of what I'm talking about thanks in advance