How do I use Extends to update a subclass from its parent?

I am currently making a 2-d platformer mario-style unity game for college in which we are supposed to use multiple design patterns. Now at the moment, I am busy making a prototype pattern (which to my understanding is a pattern from which all "enemies" could extend from to reuse certain codes or functions.

When I try to extend a class from another class, however, it does not recognize "extends".

Is there something I am missing out on? I though the ':' in the class names is equal to "Implements", am I wrong about this?

I simply need to know how I let a class extend from another class, meaning it literally uses the methods in that class.

Here is the class from which I am trying to extend: using UnityEngine; using System.Collections;

 public abstract class Prototype : MonoBehaviour {
 
     int eHealth;
     int eScore;
 
     IMoveForward moveForward;
     ILookForward lookForward;
 
     public void SetMoveBehaviour(IMoveForward m)
     {
         this.moveForward = m;
     }
 
     public void SetLookBehaviour(ILookForward l)
     {
         this.lookForward = l;
     }
 
     //void SetJumpBehaviour()
 
     public int Health
     {
         get { return eHealth; }
         set { eHealth = value; }
     }
 
     public int Score
     {
         get { return eScore; }
         set { eScore = value; }
     }
 
     void Update()
     {
         SetLookBehaviour(lookForward);
         SetMoveBehaviour(moveForward);
     }
     //  public abstract Prototype Clone();
 }

And here is the class which is supposed to extend from said class:

 using UnityEngine;
 using System.Collections;
 using System;
 
 class BasicMovement : Prototype, IMoveForward {
   
     public float _speed = .5f;
 
     //send the speed value to the move interface
     public float speed
     {
         get
         {
             return _speed;
         }
 
         set
         {
             _speed = value;
         }
     }
 
     //implement the movement method
     public void MoveCharacter(Vector2 m)
     {
         m = new Vector2(transform.localScale.x, 0) * speed;
     }
 }

This class also implements an interface called (IMoveForward) (assuming ":" is actually "implements").

Sorry if I'm being somewhat vague it's just that I am not sure what I am supposed to do. right now the classes mentioned above are all working without errors, but I have no update function (which i would like to put in the Prototype class and from there update everything)

Please let me know if I need to specify more things, and basically what I am mostly trying to ask is: How can I extend from another class, so I can update the subclass through the extended class?

Thank you for your time and once again, let me know if I need to specify things.