Access my website using external IP address

That depends. In many SMB cases, you'd not bind an external IP to the server at all. You'd configure the device at your network edge (NAT router, UTM) to act as a port forwarder or reverse proxy.

In addition to what Cliff mentioned, you might need to explicitly allow external Ip's to access you website, from IIS and also possibly from your Windows Firewall.

To add to Cliff's response, then on the server that you have forwarded the request to (in this case the webserver), you would configure the host header values so that the site in question will answer for either:
1.  All requests to *:80 (HTTP) and/or *:443 (HTTPS) [in the case of a single site web server].
2.  All requests to <host header value(s)>:80 (HTTP) OR *:<http port> (HTTP) and/or <host header value(s)>:<ssl port for site> (HTTPS) [in the case of a multi site web server]

The host header value is what you defined on your external DNS server (usually hosted - i.e. GoDaddy) for the website that you want clients to access.  You don't have to create an external DNS record if this is a single site web server.  But if this is a multi site web server, you can either:
1.  Create seperate host header values for each site (to use DNS).
2.  Create separate http port entries for each site (to use just the IP address).
3.  Create seperate host header values and seperate http port entries for each site (to use DNS or IP address)

-saige-

Thank you for you help.

Chewe..What should I do to allow external Ip's to access my website. I need the detail steps.  Because I am really new to this.

Thanks.

Please check out the following link. Assuming that this function is already active, you can scroll down to the section that shows how to make changes.

Thank you. I will try it and let you know.

Hi Chewe,

Actually I could not find any link. Can you please send it again.

Thanks.

Thank you for your help.