Why do you need to change router?
Set up should be from phone socket - filter - adsl to d link router.
Ensure there is a filter on all other phone devices in the house.
To set up the d link you will need your bt username and password - to find this - whilst you still have your bt home hub connected open IE or other browser type in 192.168.1.254 and look for set up details - you may need username and password to access router - usually admin and password 0r the password is on the hub
You may have this info in an e-mail or letter as well.
Connect the d link and access the set up page and enter your bt details.