Instructions
Click on the "Battle.net Multiplayer" button on the Diablo 2 main screen.
Log in at the prompt that appears with your Battle.net username and password.
Click on a character you want to play with to be taken to a chat room. If you have not created a character for Battle.net, the program prompts you to do so.
Click "Join" in the chat room to open a list of available games.
Click on the game from the list that appears with the player you want to play with (the player's name is listed next to the name of the game) and click "Join Game." If the game is private (not on the Join screen) type in the name of the game and the password in their respective fields on-screen to join.