Does anyone know how to install the flipclock?

Hi Nicoletteby and welcome to Apple Support.

This one works up to Mountain Lion:

http://vanillaextract.me/friday-find-the-flip-clock-screensaver

It's also here. It needs OS X 10.8 or later:

http://osxdaily.com/2012/11/28/flip-clock-screen-saver-mac-os-x/

http://9031.com/goodies/

Oh and if you're asking how to actually install Flip Clock in Mavericks and Yosemite:

http://osxdaily.com/2014/07/30/install-screen-saver-mac-os-x/

They're actually installing Flip Clock.