On this page you get a green box headed "Reserve Seats", which gives the position for each player. So, once all 4 players are logged onto the site, decide who is going to "Host" the game. The host then clicks in the green box of the position they are going to play in. Immediately a blue dialogue box pops up with a place for you to enter your Username. Once you do this and click on "OK" you will be automatically "seated" at the table.
When this happens your Username will show up in the player position you have chosen and turn blue. You then enter the Usernames of the other three players in the same way at the appropriate playing positions. At first they will appear in red. Next you click on the "Start Table" box at the bottom of the screen. Once you have clicked on "Start Table" all the names on the screen should turn blue and then you are all set and the playing screen should open with everyone "seated" at the table.
There are a few other options on the final screen. One is about "Kibitzers". These are just spectators and unless you have others who want to watch you play , turn these off. At the top of the screen you can also chose the scoring method. The default is Imps but you can change this to Matchpoints. Finally, at the bottom of the screen you will see a line saying "Message" on the left and "Chat" on the right. This is where you can send text messages to each other during or after play. You need to set the box on the far left to "Table" (it probably says "Lobby" initially) and everyone seated at the table will be able to see your chat messages.
Warning: If you are slow to bid or play you will first get a warning from the site but if you fail to react swiftly you will be dropped off the table. You can usually restore the player who has been dropped by clicking on the seat and reserving it again.
Note: If you use the "Start Table - Competitive Game" rather than "Relaxed Game" this appears to avoid the above problem and also the Game History appears to be preserved with this option.