Install RealVNC (in both computers)

Browser http://www.realvnc.com/products/free/4.1/download.html

Run vnc-4_1_2-x86_win32.exe downloaded

Enter your own password (Note: Don't set 1234 or abcd)

Get your IP of the computer will be remotely controlled (address in the Internet)

Surf http://whatismyipaddress.com/

Setup the server side (i.e. the computer will be remotely controlled)

Setup the client side (i.e. the computer will remotely control the above computer)