I just needed to charge it. Hopefully you have a 134a system. you just need to convert (with hose clamps) a car sized can of refrigerant to a schrader valve style connector. There are car kits at wallmart and such, it will have the wrong connector. Usually you can find a set of broken guages in a pawn shop. Use one of the ends and find a way to clamp it to the hose.

Now purge the line by running a bit of gas thru it. then hook it up and put a bit in. You should then feel the lines in the system. You will see frost while it is running start to form in the evaporator. Put a bit more in and watch the frost line. It eventually will go through the whole system and you will start to see it going up the tubing towards the compressor while the compressor runs. Just make sure it doesn't get to the compressor. If you get close just let a tad out.

NOTE. I am NOT a refrigerator tech, just a guy with a boat that needs to DIY. I have learned this little bit from books (thanks Richard Kollman) and talking to a friend that does home stuff for a living and talking with Frigoboat tech (my system).

Good luck.

Rich