While you can do anything you want with screen backgrounds and such to make it your own, the author went with a Star Trek theme. Have fun with it.
For icons, I found some good ones at Icon8 which distributes them under the license called Creative Commons Attribution-NoDerivs 3.0 Unported. You can find a wealth of free to use (with credit/link given) at https://icons8.com. The alarm button icon is from there.
The Mugsy icon is from the Mugsy site.
The LCARS style screens are inspired by Star Trek computer interfaces from The Next Generation onward.
The alarm screen can be any 320x240 24-bit bmp file you like. I found a red alert screen that went with the Star Trek theme.
Weather icons are from the OpenWeatherMap site which is where weather data is pulled from. The were tweaked slightly by adding a black background for use on the PyPortal.