If you want to color a picture, it must be the whole picture. If all you want to change is the board, that's the background, right? Be sure to choose the right tools for clothes. The specific tools depend on the situation. If there is a big difference between the clothes and the background color, use a magic wand and the background color should be uniform. If the edges of the clothes are regular, use the polygonal lasso tool. However, in general professional retouching design, pen tools are used more, because pen retouching changes the background and so on, and there will be no virtual edges on the edges. (i.e. enlarged edge mosaic)

After being selected (keeping the ant line state), you can press CTRL+j to generate a new layer from the contents of the selected box, so that changing the background layer will not affect the color of the clothes. However, there is also a problem with this change, that is, the color difference is large and the whole picture looks stiff and awkward. If the color difference between the clothes and the background is not too big. After the selection is created. You can press ctrl+alt+d to feather the selection. Then change the color, the edge will be more natural. Not stiff.

Simply put, your problem is to dig the clothes out of the background. What tools to use depends on the situation. Generally use a pen tool.