Which ports do I use to connect a TC in Bridge Mode to my BT HomeHub router.

I have been advised to relocate my Time Capsule (Model Type A1409 2TB) and connect it by ethernet cable to my BT Home Hub Router so that I can use it in bridge mode as a Time Machine Backup. Once I have purchased a short connecting cable ,which port do I use on the TC to make the connection?

Early 2009 iMac and OS X Yosemite