All Head, Flat Beer

So I found an old beer kit in my parents garage (The Beer Machine) and put it to use. It seemed to work fine so far, but I have a minor problem which I'm not sure how to resolve.

It's basically a 1 step brewing kit, and it's 1 piece (a large keg). There is a valve on the front to dispense the beer once it is done, but when I do it comes out all as foam, leaving me with a tall glass of head. I can wait for it to subside and end up with half a glass of beer, but then it is completely flat (blegh). Is there too much pressure inside, or what?

Thanks, guys. If this works then I should be doing more brewing in the future. I find it is a lot like baking, which is another activity I enjoy.

I think you still need to bottle it. You need to add priming sugar and let the yeast carbonate it once it's capped up tight.

what ingredients did you use and how old were they? how long did it ferment?

Thanks! I guess I'll need to bottle it then. I was kinda hoping I could just keep the whole keg in the fridge and avoid the bottling process. The directions with the kit don't say anything about bottling either.

And I used all new ingredients. I figured that the original yeast was certainly expired.

was it cold for more than a day? CO2 sometimes takes time to go properly into suspension(the big head is a classic sign)