Unity C# Simple Move Script

using UnityEngine;
using System.Collections;

public class ScriptNameHere : MonoBehaviour
{
    public float moveSpeed;//If you're going to edit this variable in a start function like how Aaron did, then make this variable private

    void FixedUpdate()//FixedUpdate should be used instead of Update while dealing with a RigidBody
    {
        float h = Input.GetAxis("Horizontal");
        float v = Input.GetAxis("Vertical");
        Rigidbody rb = GetComponent<Rigidbody>();
        rb.AddForce(h * moveSpeed * Time.fixedDeltaTime, 0.0f, v * moveSpeed * Time.fixedDeltaTime);//Make sure you have a RigidBody
    }
}