Rocket League Xbox – How To Join A Private Match
From the Rocket League start screen, press “A” on the “PLAY” option. This brings up the “PLAY” menu. Navigate to and select the “CUSTOM GAMES” box. From the “CUSTOM GAMES” screen, move to and select the “PRIVATE MATCH” box and then select “JOIN PRIVATE MATCH
In the “JOIN PRIVATE MATCH” pop-up, enter the Game Name and Password provided by your opponent in your Rival Game Page chat box. Then click the “JOIN” button.
From the “CHOOSE TEAM” screen you can either select a team color or click “AUTO” for a random color selection. When your opponent is also ready, your game will begin automatically.