Wow. Can’t tell what caused this major damage, lifeline damage due to poor pruning shown above, frost split, or animal attack. Likely the first one, possibly the other two..
Realistically this will take a long time to heal, if at all. Much as I try to save azaleas, thinking this one should be put aside, dug into the garden in a 70/30 bark/peat mix and see if it survives.
If you want to try to save as is….Get materials at hand first… then do the following. . Gently and thoroughly clean out the affected areas with water and a toothbrush. Let dry completely. Then heat up some canning wax, just to the liquid stage so it’s not super hot, take an old paintbrush and seal the entire area, overlapping the bark at least an inch. While still warm, wrap the entire trunk over the wax tightly with 1” grafting tape or parafilm, overlapping above and below the wounds. This must be water tight to work, so keep everything snug and overlapping.
Then treat the tree as normal. Don’t let it freeze. Not major pruning for two years. Once the wax and tape fall Orr, reseal again. Etc
Honestly would choose the first option. Then get an undamaged tree or better still 3-4 to learn on.
Good Luck
DSD sends