As a clue, we can tell you that White played one of Nxg6, Ncd5, f3 or Rae1. Which brought disaster?
The relevance of a 'White to play and lose' position is, of course, that games are essentially lost by bad play rather than won by brilliance. You cannot lose without making a mistake. Whereas one only rarely has the opportunity to deliver a 'White to play and win' finish, almost every move gives an opportunity to lose. So
ch08out-harts-nws losing practice, and learning how to avoid it, is a basic skill.
Grandmaster Benko fouled up with 1. Nxg6?? when the game ended 1 . . . Qxg2+] and White resigned. 2. Kxg2 Bf3+ 3. Kg1 Nh3 is mate.