how to supply power with battery?

I’m using tx2 board as companion for drone and have to supply power with 6 cell battery.
I connected 6 cell battery to BEC that supply 12V 4A
so I need to know where I put that BEC line.
if u have a pictures about it, post or send me plz

Hi, assume you are talking about TX2 devkit, there is a DC jack on board, that’s the input power supply to whole system.

oh that means I should cut the DC jack line and connect to BEC(supply from 6cell battery)?

Yes, it should work.