I have taken the old fixture off the wall and have a square box with a vertical metal strip down the middle and a white and a black wire hte ground wire appears to be folded inside the box with a wire connector. The new fixture looks the same as the old one except it shows it connected to a octagonal box with hardware that forms a cross. It has a black wire , a white wire and a bare wire. Is it possible to mount the new one somehow and should I find the bare wire in the old bos an connect it to the new bare wire and connect it with a wire connector. This is probably basic but I do not usually do electrical repairs.