To upload your high score to the online database, just go to the Score Details page (within the game) and select Upload. You can enter a name and a comment. Note that only score made with a release >=2.2 can be uploaded (The replay file is needed). To watch a replay (remote or local), go to the Score Details and select Replay.
Hint: In the Online Score page, you can scrolldown up to the 99th player.