How do I watch itv hd with sky plus hd?

Try sitting in front of it and turning it on.

(You need to more explicit – you appear to have a problem but you have not described it.)

I was going to say turn to the channel , sit down and enjoy .
But < make sure you have you done this .
You can manually update sky+ and sky+HD . Press and hold backup on the box ( not remote ) keep holding it and switch it off at the wall , wait a few seconds and turn it back on ( keep hold of backup ) switch sky back on . It should now have a black update screen let go of backup and leave sky alone until it performs the update , this may take 30 seconds to 5 minutes . It will maybe switch off and reboot or it could just go to channel 998 , hopefully you have the new viewing card by now .
Another secret to sky is : If you get no signal being received turn off the LNB instead of paying sky or the phone bill . : Press services , 4 , 01 and select press 1 . Go to LNB setup , and turn both bottom options off save then back on . You can also do other setup things, sky like to keep this quiet and only to the engineers