Obtain a bow by crafting one yourself, or purchasing one from another player via trade or the broker in town.
You may also purchase a basic but weak one from the weapon vendor.
You will also need some arrows which can be bought from the utility vendor.
Equip Your Bow
Take Your Best Shot
Aiming Your Bow
Use the white reticle located within the charge circle to aim your bow.
You will have to account for your arrow dropping due to gravity, which is also affected by the strength of your bow.