A serger can be tricky to thread. I have a Baby Loc and love it for it's air-threading system. I would have loved ANY serger that came to me out of the blue though and Viking/Husqvarna is an awesome brand. I have one of their embroidery/sewing machines and love it.
Welcome to the board! btw.
I'd recommend you find a H/V dealer in your area. Since you didn't buy the machine from them you'll have to pay a small fee but I'm sure they'll offer a class in the basic operation of your serger. They'll be able to get you a manual as well. What you'll pay for the lesson and manual will be well worth the price, trust me.
I didn't understand why I should get a serger at first and asked here at the board. After having mine now for a year I can't imagine not having it. I make entire items using only the serger. It's not a necessity but it sure makes it fun!
http://www.husqvarnaviking.com/us/421.htm This might help in the meantime. Maybe one of these is very similar to yours.
Good luck and be sure to come back and visit us.