Having trouble with a third person camera script

I have been following a ton of tutorials because I’m new to Unity and I feel like I’ve gotten the hang of it, but while making a third person script for a game I’m making for my collegeclass I ran into some errors that I’m not sure how to fix. The only thing I can come up with that’s missing is a LookAt reference but I can’t figure out how to fix that at this point, I’d love all the help I can get.

The errors I get:
6x
Some scripts have compilation errors which may prevent obsolete API usages to get updated. Obsolete API updating will continue automatically after these errors get fixed.
and
1x
Assets/ThirdPersonCameraScript.cs(23,38): error CS0176: Static member `UnityEngine.Camera.main’ cannot be accessed with an instance reference, qualify it with a type name instead
1x
Error CS0176 Member ‘Camera.main’ cannot be accessed with an instance reference; qualify it with a type name instead

This is my script:

using UnityEngine;
using System.Collections;

public class ThirdPersonCameraScript : MonoBehaviour
{
private const float Y_ANGLE_MIN = 0.0f;
private const float Y_ANGLE_MAX = 50.0f;

public Transform lookAt;
public Transform camTransform;

private Camera Cam;

private float distance = 10.0f;
private float currentX = 0.0f;
private float currentY = 0.0f;
private float sensitivityX = 4.0f;
private float sensivityY = 1.0f;

private void start()
{
    camTransform = transform;
    Cam = GetComponent<Camera>().main;

}

private void Update()
{
    currentX += Input.GetAxis("Mouse X");
    currentY += Input.GetAxis("Mouse Y");

    currentY = Mathf.Clamp(currentY, Y_ANGLE_MIN, Y_ANGLE_MAX);
}

private void LateUpdate()
{
    Vector3 dir = new Vector3(0, 0, -distance);
    Quaternion rotation = Quaternion.Euler(currentY, currentX, 0);
    camTransform.position = lookAt.position + rotation * dir;
    camTransform.LookAt(lookAt.position);
}

}

I’m not sure what you want to do with the cam variable but the reference is a bit strange. If you want a reference to the main camera use:
Camera.main