You learned the chess rules and want to become better? Great! A good point to start is solving puzzles, to get a firmer grip on how the pieces move and how they coordinate.
This app contains about 650 mate in 1 puzzles: its your turn and you have to find the move which immediately checkmates your opponent. You can be quite sure: when you finished this course, you are prepared for the next level.
The app is completely free, no ads and no internet connection necessary, once installed.