Points for win/lose ?

Unsure how points are allocated re wins & loses. Okay, no big deal but just played 2 tounament games against a player 100 points better. I won the first & lost the second. Overall my rating went down. How does that work ? Silly me assumed my rating after the two games would improve, but no, as I said, it went down, why. Does the length of game have a bearing ? Game I won was just under 40 moves and the game I lost was 41 moves. Or is it more complex than that ?   Remain puzzled.  Have played in total 93 games.