Create a new transparent layer, use the rectangle selection tool and circle the pattern you want. Right mouse button, fill in, and then select a color with the content. Then a color adjustment window will pop up, select the color you want and confirm. Just adjust the opacity on the panel.

If you want to create a beautiful picture of Xiu Xiu, you can create a new picture → customize the color, select the color you want → the cutting tool, and cut out any shape you want. You can adjust the shape yourself → cut it and save it → open the figure picture, right-click to insert the color bar → you can adjust the color bar shape appropriately and then adjust the transparency.