Change a t-shirt color in X4 photo paint

Hi, I just came across this community :) I am color blind and need help. I need to make t-shirt templates of ever color t-shirt I carry, as I am a screen printer. I have taken a picture of one blank t shirt (royal blue) laid out flat, I removed the background in photo paint for X4. I now have the t-shirt file I want and now I need to change the color of this shirt to make 12 different color t-shirt files. I CANNOT do this without someone walking me through the steps, as I don't know how to do this process. And I MUST be able to select the color I need for each shirt by entering the RGB color numbers, as I am color blind and cannot just alter colors using a color slider bar of any kind. I need to know a process where I can enter the colors through RGB numbers without sliding any bars to adjust colors. I have all of the RGB numbers I need for every t-shirt.  Thank you for the time.