Cheap Loco pick ups

Hi all.   I have one of those cheap and cheerful 0-4-0 Loco’s that I would like to convert to DCC.But I saw a YouTube video which didn’t fully explain where the pick ups were? After unhooking the clip holding the motor in position, and cutting off the bits that protect the tv reception, It went something like “ you have to cut the connection “ , on the chassis. Red and black to the track etc, but I couldn’t see where the was. Would someone please advise me.  Best wishes Kevin