How to round images.
You can use any image.
I'm gunna use this one.
Go to Selection, and under Selection type choose Rounded Rectangle.
Then click at the top left corner and drag it to the bottom right corner. Like this.
Then press Delete on your keyboard, and use the backround eraser to take out the white color, or keep it.
Then press CTRL+D, and put in any color you want in the White/Grey checkered areas.
Those represent that the backround is transparent.