At the moment a private table is not possible. The answers in the giant feedback thread may influence if that will change.
How to do it anyway: Make sure that you mark each other as friends in the game. Then sombody (the host, whose card selection will be used) has to start a table ("New Table", then "Create Table", make sure to adjust the max player count). Then all that player's friends see that player in the Matching tab, where they can join the game (first as spectators, then as players). If somebody else joins in the meantime, the host can kick them off the table, maybe with a short explanation before ("Waiting for friends").
The option with the bots (as explained by blamelewis) would be another way.
If you have more questions, feel free to ask.