How to set an Animator Boolean with JavaScript

So far I have this script, but when I attempt to have the Shift key trigger a boolean to toggle a run animation, and have it toggled back off once the key is released, I get the error "‘SetBool’ is not a member of ‘System.Type’. Can Anyone help? I have a picture added for further clarity. Please keep in mind, that I know almost nothing about how the Animator Works in the first place, so please keep any explanations to a “So-Easy-A-Caveman-Could-Do-It” level.

#pragma strict

var TheAnimator = Animator;

function Update () 

{
	if (Input.GetKeyDown(KeyCode.LeftShift) || Input.GetKeyDown(KeyCode.RightShift))
	{
		Sprints();
	}
	else
	{
		NoSprints();
	}
}

function Sprints()
{
	TheAnimator.SetBool("IsRunning", true);
}

function NoSprints()
{
	TheAnimator.SetBool("IsRunning", false);
}

Try do it this way:

#pragma strict

var ThePlayer : GameObject; // Game object that have animator

ThePlayer = gameObject.Find("game_object_name");
 
var TheAnimator = Animator;

TheAnimator = ThePlayer.GetComponent(Animator);
 
function Update () 
 
{
    if (Input.GetKeyDown(KeyCode.LeftShift) || Input.GetKeyDown(KeyCode.RightShift))
    {
        Sprints();
    }
    else
    {
        NoSprints();
    }
}
 
function Sprints()
{
    ThePlayer.TheAnimator.SetBool("IsRunning", true);
}
 
function NoSprints()
{
    ThePlayer.TheAnimator.SetBool("IsRunning", false);
}