rigidbody deprecated confusion issue C#.

Hi all, trying to add force to a textbox in C#, for whatever reason while I follow either a Unity official tutorial or one written by someone else, something is not right.

So, I have an object on my screen, its just a text box. I have a rigidbody3d object applied to it, Following the templates that I have seen in C#, this is supposed to work:

using UnityEngine;
using System.Collections;

public class WordMover : MonoBehaviour {

public float power = 100;
public Rigidbody rb3D;

// Use this for initialization
void Start () {
    
    rb3D.GetComponent<Rigidbody>();
    rb3D.AddForce(Vector3.up * power, ForceMode.Acceleration);

}

This is according to what I saw at:
http://docs.unity3d.com/ScriptReference/Rigidbody.AddForce.html

This throws the following error:

UnassignedReferenceException: The variable rb3D of WordMover has not been assigned.
You probably need to assign the rb3D variable of the WordMover script in the inspector.

I don’t get it, the script is sitting on the object that I want moved, what am I missing here, what is it looking for?.

Then I looked at one of Unity’s official video tutorials and it uses some sort of deprecated way of doing it:

59979-capture.png

I tried doing it this way and VisualStudio told me the following:

CS0619 C# ‘Component.rigidbody’ is obsolete: ‘Property rigidbody has been deprecated. Use GetComponent() instead. (UnityUpgradable)’

Its just a syntax error.

Change:

rb3D.GetComponent<Rigidbody>();

To:

rb3D = GetComponent<Rigidbody>();