⇒ After you have registered you will have to create your own company.
⇒ Choose a name for your mercenary company which other players in the game will recognize you by. Then choose an available portrait from the list that best suits you.
⇒ After you have chosen a nickname you can then, if you wish, set a fore- and surname for your mercenary.
⇒ Last but not least, you will also have to select a class for your mercenary. There are 5 different classes: Scout, commando, sniper, gunner, and soldier. Every class has its advantages and disadvantages, which will be displayed when you hover the mouse over the class symbol. For example, commandos are very skilled with small weapons, like pistols, while riflemen start the game with a machine-gun.
⇒ After you have created your company you will go directly into an introductory mission in which the basics of the game will be explained to you. In total there are three various introductory missions which teach you all of the intricacies of the game bit by bit. These can be repeated at any time.
You can find further information in the official JAO forum.