I'm new to chess and I don't have much knowledge. But I was playing a game as Black, and I was up by a lot of material and played Nxc4 to capture White's last bishop. The game ended in a stalemate, even though the king was trapped, I think.
[FEN "2qk1b2/4n2p/1n3p2/3p4/b1BK4/5r2/7r/8 b - - 0 1"]
Can anyone explain to me please why this happened and why I didn't win?