duo tone swatch (shades of green)

I want to help but I have to admit that I could not understand what you have in mind. Perhaps you want to make a conventional duotone consisting of a particular red and particular green. If that is the case, the first thing to do is to convert the image to grayscale (Image > Mode > Grayscale.

Then choose Image > Mode > Duotone. You can insert your chosen colors and by clicking on the Curve for each, decide on the distribution and intensity of color in the image and the image contrast.

Usually, the most successful duotones consist of one dominant color and one less intense. Deep red and green you mentioned are an unusual pair. If this is not what you have in mind, post an image that has the effect you want to duplicate and we will try to advise you about the technique required. One thing more: If you click on the down arrow in Preset, (It says Custom I the illustration above) you will see of list of preset duotones of various color combinations and intensity.

If you would like more information about duotones and preparing the files for press, I have written a Tech Sheet on the subject for my students and will post it for you.