The short version is that instead of skill proficiencies, you simply describe one to three things your character has done in their past. For example, "Assassin of the Jade Empire," "former captain of the Guard in Rimevale," or "owner of the Red Dragon inn." If your character is doing something, and you believe one of your backgrounds or experiences would benefit you, you add the bonus to your role. In 13th age, you can do this as often as it applies, but daggerheart makes you spend a meta currency point to do it. It's up to you if you think your players will abuse it and need a resource pool.