Join and Create games
Click "Games" to open the games menu. While "My Games" shows your currently running games with all important information, "New Games" is the place to create or join more games. Games you don't play anymore or that have ended can be moved to the archive. The archive will start to clear out after a few days (or weeks) of sending a game there.
Once you click "New Games" you can simply select one of the games you see offered. You can however search for a specific ID (if a friend opened up a game he'd like you to join) or use the "search options" filter for example for a special type of map.
To create a game, click the "Create" cross on the upper right. You can name your game and add a description. While the name is a must, the description is optional.
If you scroll further down, you will see different options that might be used when you create a game: Frontline Pioneer is only accessable for players with a Frontline Pioneer Account. Elite AI (Artificial Intelligence, meaning those nations that are not handled by players but by the engine) is a so called "gold feature" which means that the use of this feature subtracts 5000g from your account as well as from each player who joins this round. If you have a Premium account, joining and creating "gold rounds" is for free. Country selection lets you set a game where everyone can pick his or her favourite nation.