If you mean where to link the animation, there is a SpecialAnimation field under the Skill Config section of your spear throwing skill.
You have to put a string there, signifying the animation (for example "SpearThrow") and then in the character animation table, under one of the SpecialAnm slots of Spear section put the link to the ACTUAL animation file + your custom string under it. Then give that skill to your character somehow (via mastery skill or item) and if you did everything right, the skill should trigger the animation.