How do I change to https://secure.mydomain.com

I use a ssl cert with https://secure.mydomain.com.  The problem is when I turn on ssl in the config.sys file it takes me to https://mydomain.com.  In the commmonhelper.cs file I found the following statement were I believe I should make changes
         if (useSsl)
            {
                if (!String.IsNullOrEmpty(ConfigurationManager.AppSettings["SharedSSL"]))
                {
                    //shared SSL
                    result = ConfigurationManager.AppSettings["SharedSSL"];
                }
                else
                {
                    //SSL
                    result = result.Replace("http:/", "https:/");
                }
            }

Do I change {result = result.Replace("http:/", "https:/")} to {result = result.Replace("http:/", "https://secure/")} or do I change it to smething else?
All ready changed ti in the productsharedbutton.ascx.cs.
Are there any other changes that I have to make?

Thanks in advance