Yeah you have to remove the outer casing to install the logic board. Simply pull back the white sticker and lift the clip to remove the ribbon cable. Then remove the 5 small screws so you can take off the top cover and the shiny bottom cover.
The logic board you have now, won't work with the replacement motherboard you are getting unless you remarry it. So that's why I mentioned having the logic board included with the replacement motherboard, to save you some work. But if it's not available you should do a search for remarrying the logic board.