Hey Dennis, you need some info. One, what inks are you going to use? You may need the "color numbers" for those to put into Photoshop, as well as setting dot gain, and other issues too involved to start typing here. Having the correct settings will help your image when you convert to CMYK. You must start with an RGB image. It's best that the original file is RGB, but if you only have a CYMK image, then convert to RGB before you start. You may want to check the "other" board a lot of us used, and some still do, and look it up there. There was a guy named Fred (who was banned for a posting faux pas, porn) but who often wrote concise instructions for things like this. In fact, he only did CYMK for his work, or so he said. He also posted a set of Transfer curves which he had thoroughly test FOR HIS SETUP which may give you an idea of what that's all about. Much to learn to do it this way...
Steve