Here's how it sounds:
And here is a backing track, so you can play on top of it:
You may download the music sheet as PDF, or in MuseScore format, so you can edit, transpose, transcribe and customize it to your own needs.
Click the image to download the format you want:
Outside Russia, "Korobeiniki" is widely known as the "Tetris theme song", from its appearance in Nintendo's 1989 version of the game.
More info about it in Wikipedia.
Here's the original version:
Cheers and happy learning,