Nice camera
It's very good to start taking pix with the Nik II because you learn so much about the settings you should be using. I do not any pdf files like you asked for, but I can recommend you buy an old book or two on underwater photography (check ebay or local second hand bookshops) because you will learn much more, much faster, and get much better results. Many of the older books are written for users of cameras like the Nik II, and explain the settings very well, and this may be better than trying to find instructions for just the Nik II. I think teh bbokos I had were by Jim Church.
Be very careful with your camera, it is worth good money still. Get an experienced person to show you how to clean it properly after every use, learn how to look after the o-ring seals, and get a routine going.
Good luck and enjoy it.