Drag in a image into the window.
Select Free Select Tool which looks like a lasso. Add dots around the edge of the area which you want to edit.
Once you have selected everything you want, you can either hover of the first dot. If it goes orange then click on it. If it doesn't, drag the last dot so that it intersects with the line of the first dot. Then right click, click select and then click From Path.
Once you have done this, the edge should have moving dots
Click Colors and then Colorize. Change the settings for shadows, highlights and midtones till you find soemthing you're happy with.