First let me explain the steps I did from the very beginning till the end (also to help others):
1- I requested a static IP from my ISP.
2- Inserted that static ip to the A Record of mydomain.com
3- I installed IIS and Web Deploy 3.0
4- I setup new web site in the IIS Manager with IP address as my IPv4 address and port 80 and reconfigured .NET Framework version to 4.0 from the "Application Pools" tab in IIS Manager.
5- I added new Windows Firewall Inbound Rule as Predefined and chose World Wide Web Services(Http)
6- I added a simple index.html file to the root folder of my domain as testing purposes. ( To help others: With these steps I also accomplished publishing my webApplication with Visual Studio 2012 successfully but for now I'm testing with index.html file which consists just "Hello World" )
7- In my router settings; I reconfigured "Port Forwarding" as -> Local IP: 192.168.0.12 (IPv4 addr) & Start Port:80 & End Port:80 & Protocol:TCP
Now here is my detailed problem:
When I enter mydomain.com: It shows "Site Under Construction" Page. (which shows my domain sellers information)
When a PC in my LAN enters mydomain.com: it shows "Hello World", no problem here.
When anybody else enters mydomain.com: They told me that they see "IIS7 Welcome Page"
I think one more step will solve both 1st and 3rd problem, however I got stuck despite every investigation I have made.
I'll be very glad if you give any solutions about the problem, Thank You