You either need to get an Openreach Modem, which you can get from auction sites for about £20 or return the router and buy a VDSLModem/Router.
If you get the Openreach modem it is simply a case of plugging it into the phone socket and then connecting your router to it.
If you get a VDS Modem/Router you need to enter a couple of settings but it is easy enough to do and an explantion of how to do that can be supplied from the forum members.
Setting up another router to work in bridge mode with the Homehub gives you two seperate wireless networks which I don't think is what you want.
What you possibly mean is setting it up as your wireless access point. This could be done but it would not in my opinion be the best option for you. If you are wanting to keep and use the D6200 I would buy an Openreach modem and use it that way. It is far easier to set up and does away with the Homehub 5 all together.
The Homehub 5 does not have a modem only mode so can not be set up to be just a modem.
You should be able to use the netgear in that fashion.
Turn of the Home Hub Wifi and the netgear is doing most of the routing.