Hi Michal, and welcome!
To record your game results, simply open the corresponding scenario page.
Just below the tags (and above the historical background), you'll see a line beginning with "Victory Results."
Clicking the upward arrow will award a victory to the top army (the army at the top of both the image and Vassal).
Conversely, clicking the downward arrow will award a victory to the army at the bottom.
The entry is calculated immediately.
You can enter multiple results by clicking the arrows repeatedly.
Only registered users (logged in to the site) can enter new results.
Let me know if you encounter any problems, and thanks for adding to our game database, which has now surpassed "14,500"!