How do I select class, and what class should I select?

You can select your first class when you reach level 6 and build the Class Hall building. After this you can then change class at any time with a class change item that you can buy as part of a package but costs money. You change class in the class hall using the 'Class' option and then select the class you want to change to.

You get a chance to change class for free though when you hit level 10, 13, 16, 19, 22 and 25 but you must take the opportunity when it pops up or you lose the free chance.

The class you want to be will depend on how you play the game. Raider depends on attacking others for their income. Farmer has buffs to local resource production and trader earns more money to buy resources with. Trader can also help other a little. The new Builder class has improved building perks. Check the class page in the guide for more details on these.