I've searched various websites where Nexxtech appeared, but unfortunately, no information could be gathered. There is no manual posted for the camera you're having. However, try contacting the seller of the camera. He should provide additional information on how to contact the original manufacturers to obtain a owners guide.
Alternatively, use the Google search and type the exact model number of your camera followed by owners manual/guide. You will have more luck this way than using the term you've posted on the official website.