You'll need to arrange for incoming access on any firewalls that may be running on your office LAN. Open a pass through for port 5800 (or 5900) by default for TightVNC and then find some means of filtering to only allow connections from your home IP address (or range of addresses).
Also, you'll need to make sure you're running the Tight VNC program on your home machine too, unless you want to use a browser to access it.