If you did not purchase a WildCard SSL to secure subdomains then you will need to set up an IIS web site for each sub domain and redirect it to the original domain.
Under IIS create a Web Site titled yoursubdomain.com and point it to the Live Site folder for its home directory. Our example is BirdDogSW.com.
Type the name of your subdomain web site.
Type the Host Header value of your web site.
Browse the path to the Live site folder for the Home Directory and click next.
Select Run scripts such as Asp. Click next.
Right mouse click the newly created subdomain web site and select Properties.
Click on the Home Directoty tab and then select the 'A redirection to a URL' radio button.
Now key in the URL that you want this web site redirected to. Put a check in 'The exact URL entered above'
check box. Also at this juncture make sure that the Application Pool for the redirect site is the same pool
as the site it is pointed to or create its own Application Pool.
Click Ok and the redirection is completed.