Hey @mety-go, thank you for the comment.
When you go to the muliplayer page, there is this "copy" button that copies the link for you. (Or if you are on mobile, you should see a "share" button as well).
After this once your friends join the room, you should be able to see a "start game" button on the right corner. Once you click it the game should start (and so the fun!) :D
Please let us know if you are still having problems.