Queen in end games
Bring your king into the action to support your pawns and provide additional threats your opponent's king
Centralize Your Queen
Push Passed Pawns
@1
"I am so bad when there is only pawns and our queens"
++ Queen endgames are hard. You have to calculate all possible checks.
"even if i have an extra rook" ++ Then trade queens and win with your extra rook.
"the king should be in the corner" ++ The king should be in a safe place.
"the queen should be around the king"
++ The queen should be in the center, or supporting a passed pawn if you have one.
This tip is I think the most important. If you are up a piece, or even just a few pawns, look for a tactic that will take the queens off the board. This can be a skewer, pin, or fork.
Here's an example:
Another example:
One more:
As you can see, there are a multitude of tactics you can employ in queen endgames. The best way to get good at this is to simply do puzzles. You can filter your puzzles to only queen endgames, and this will help a lot.