Unzip the file and right click on the .SCR file and select Install.

OR -  Put the  SCR file into the windows or windows/system32 directory (also recommended ) for x32 systems,  
or into the SysWOW64 directory if you have a  x64 system.

To use the screen saver just select it in "Screensavers" in "Personlization" window
 
Delete the SCR file from wherever you placed it in, as in  above,  to delete the Screensaver.  