Arduino + EtherCard enc28j60 + 2 thermistors + POST how to?

Hi there. I managed to do what i wanted by adding the following:

 client.print("<iframe src='http://domain.tld/a/alin.php?tur=");
          client.print(Tc);
          client.print("&retur=");
          client.print(Tr);
          client.print("' width='1' height='1' name='DataBox'>");
          client.print("</iframe>");

And now it send the data to my php file hosted on an external server and the php file inserts the data into mysql.

Now i have another problem: How do i make it to do this every x seconds? I triyed addng delay(5000); but if i do this it won't work.

Any sugestions?