When you are ahead in material, the “easy way”, is to exchanged off until your extra pieces or pawns can not be stopped.  Basically   Simplify to Win

Here Blacks plan should be to exchange Queens, then advance the b pawn. When his King moves to stop it, push the f pawn. He can not stop both  eg.

1. … Qc1  2.Qxc1 Bxc1   3.Kf2 b5  4.Ke2 f5  5.gxf5 gxf5  6.Kd3 b4  7.Kc4 f4

– without the help of the bishop, king or other pawns, one of these pawns will Queen

8.Kxb4 f3  9.Kc3 f2  10.Kd3 f1Q+ 11.Kc2 Qxh3  12.Kxc1 Qh2  13.Kd1 Kf6  14. Kc1 Ke5  15.Kb1 Kd4  16.Ka1 Kc3 17.Kb1 Qb2#