There are a few ways to blend colors in Photoshop. One way is to use the blending modes. The blending modes can be Vibrant, Soft Light, Hard Light, and Screen. The Soft Light mode blends colors together more than the other modes.
In Photoshop, you can use a blend mode to combine different colors together. For example, if you want to make a picture that is both blurred and bright, you would use the Blur filter.
To blend with a brush, use your hands to mix the colors together, and then use the brush to apply the mixture to the skin.