BT Infinity with Cisco Linksys E4200

What is the best way to set up the Cisco Linksys E4200 with BT Infinity ?

I had BT Infinity installed the other day and want to use this router.

I bought it many months ago for Infinity and only now can I finally use it, it's a V1.

I have the BT supplied modem HG612 (3B).

Thanks in advance.