I was given a Dressmaker Machine too. I have sent for the manual. The website is Sewusa.com
it cost $10 + shipping. My machine is C55A. ZigZag machine. I was able to get the instructions free on that web site on how to thread it. This helped me a lot.
I have posted a picture of it. My concern was the left needle position. People have helped me understanding why it is set up that way.
Phyllis