Very Simple indeed, just a bunch of led’s and resistors stuck together to create a Christmas tree. The project is very recommended to beginners. You can just build one to see how it works or you can make as many of them as you need(maybe you want to decorate something with these). The top led is a red/green flashing led, you can buy this from anywhere and if you connect them to power they will start blinking. The diagram though very simple is in the Flickr set. Good luck building it.

Simple Led Christmass Tree