Need guidance to connect R7000 with Advanced Tomato as Acess point to Vodafone modem

Hello Friends

I am hoping that you may be able to help me install StrongVPN using OpenVPN on a Nighthawk R7000 with Advanced Tomato.

Internet connection is Vodafone Fibre.

Have found a few guides but have not been able to succeed.

BTW I am 72 yo so please be a bit gentle with me as, although I am still learning I don't have your knowledge base.

Have flashed the R7000 with Advanced Tomato Ok. So far have been able to disable the WAN on the R7000 and use a network cable from the Vodafone LAN port to R7000 LAN port to start to get somewhere but really need some help (sort of plain English so as I can understand).

Is there any more basic info you need from me?.

Thanks in advance.