then you can try explaining why the double threat doesn't work one move earlier with 3..d5 ;) this kind of exercises can win you -MANY- games with low rated players.
As the old saying goes, Games with Bishops of opposite color are usually drawn.

It might have been possible to win the endgame. 38. Kf2 would have been my choice, activating the king.
The only certain way to obtain a win in Bishops of opposite colors endings is to get ones King to be able to attack the back pawn and Bishop when the Bishop has less than 3 squares to operate on to defend and the King is unable to support the back pawn. I usually will offer a draw unless I can get this circumstance to come to pass.
Win for white in the endgame until move 35. I dont think rush pushinh the c5 pawn is correct way. By far the best is to create 2nd weakness . That is to push kingside pawn also where white king should take care the the black f pawn first then pushing g and h pawn. With c, g and h pawn to deal. Its tough for black king and bishop. My evaluation.. not all opposite color bishop ending is drawn and also in this game.

There were many suggestions already. Now, I only glanced at a certain point in the game, but the move 37. c8=Q makes absolutely no sense to me, unless you simply missed the fact that black can take the queen with his bishop.
Instead, 37. Kf2 was clearly the correct move. You just threw away a passed pawn on the seventh rank for - nothing. 37. Kf2, on the other hand, leaves black almost in zugzwang. After 37... Bg4, just 38. h4. One simple idea is to play c8=Q at the right moment, and after Bxc8 take the pawn on f3 with your king. Black simply can't handle the situation, 3 extra pawns should be enough.
If you think getting into Bishop of opposite color endings and not getting the draw or win are frustrating, WGM J. Polgar had a game where she botched a K+N v K+2p ending for a draw I believe where if she would have let the pieces go to the opposite sides of the board from where they were, she would have drawn and instead resigned i believe was the result.
Bottom line, even endgame positions that can draw easily can be missed by GMs as well as amateurs.

There were many suggestions already. Now, I only glanced at a certain point in the game, but the move 37. c8=Q makes absolutely no sense to me, unless you simply missed the fact that black can take the queen with his bishop.
Instead, 37. Kf2 was clearly the correct move. You just threw away a passed pawn on the seventh rank for - nothing. 37. Kf2, on the other hand, leaves black almost in zugzwang. After 37... Bg4, just 38. h4. One simple idea is to play c8=Q at the right moment, and after Bxc8 take the pawn on f3 with your king. Black simply can't handle the situation, 3 extra pawns should be enough.
Exactly this.
The endgame was completely winning if White had seen this.
black could have won with 4..d5 attacking the queen and the bishop simultaneously.