Please can i have some hints for this last exercise

package com.example.model;

import java.util.List;

public class Course {
  private String mName;
  private List<Video> mVideos; 

  public Course(String name, List<Video> videos) {
    mName = name;
    mVideos = videos;
  }

  public String getName() {
    return mName;
  }

  public List<Video> getVideos() {
    return mVideos;
  }

}

package com.example.model;

public class Video {
  private String mTitle;

  public Video(String title) {
    mTitle = title;
  }

  public String getTitle() {
    return mTitle;
  }

  public void setTitle(String title) {
    mTitle = title;
  }

}

import com.example.model.Course;
import com.example.model.Video;
import java.util.List;

import java.util.Map;
import java.util.HashMap;

public class QuickFix {

  public void addForgottenVideo(Course course) {
    // TODO(1):  Create a new video called "The Beginning Bits"
      Video tbb = new Video("The Beginning Bits");
    // TODO(2):  Add the newly created video to the course videos as the second video.
    List<Video> mVideos =  course.getVideos();
    mVideos.add(1,tbb);
  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
    Map<String, Video> a = videosByTitle(course);


  }

  public Map<String, Video> videosByTitle(Course course) {
    Map<String, Video> a = new HashMap<>();
     List<Video> mVideos =  course.getVideos();

    int count = mVideos.size();
    int scount= 0;
    while(scount != count) {
      a.put(mVideos.get(scount).getTitle(), mVideos.get(scount));
      scount++;
    }



    return a;
  }

}