Hi! I went to that site: http://synchring.tk/index.htm using firefox, then I tried right-click and selected 'show page source'. Have you tried that yet? I wonder how you created and saved your source? Sorry, I am new here also, I haven't got a clue what to tell you about the DNS change. Good luck!
You have to change the nameservers that your domain name points to. You should be able to do this from your registrar. Check their website for information. The heliohost nameservers are ns1.heliohost.org and ns2.heliohost.org. Check this page on the wiki for more information. http://wiki.helionet.org/Parked,_Addon_and_Sub_Domains