Quests are a task given to a player by a npc with a reward upon completion. NPC's with an ! over their name has a quest available. Quests can be harvest x amount of materials or kill x many mobs. Rewards vary between items, money and experience.
Farsight Recipe : First of All, you need to talk with Jarekai at Armistin and ask for a quest, he will send you to kill 50 Desert Tortug (You can find them 2 maps north from Armistin, then 1 map to the left, then 1 to the right.
After you have killed the 50 Desert Tortug, go back to Armistin and talk with Jarekai, he will send you again to kill 100 more Desert Tortug and the quest "Tortug Overrun", after you have slain the tortugs go back to Jarekai and he will give you :
5000 exp and the Farsight Recipe.