VPN setting

i live at indonesia
i use windows server 2003 and adsl modem and don’t have static public ip,so i just have dinamic ip, how can i setup my computer to be vpn server?what must i do?i have client at US need to connect with my computer directly to upgrage software.
what port usually use at vpn connection?
is need for me to have vpn router?
is need some special software for that?
please help me with step by step setting up.
thank you