For all programs: Your GUI does not need to follow any particular design. It should be logical and obvious how to use. I'm not grading you on style. But if you want to improve the appearance of your GUI above the default, go ahead.
If a variable name is specified for a component, you should use it.
To take a screenshot on a Mac: Command+Shift+4 lets you select an area of screen on a Mac. Select an area, and the screenshot will be saved your desktop. Screenshots on Windows: use Window's Snipping Tool.