Access variables from superclass while extending a library

I'm trying to access the variables of a superclass from a library. I'm currently using ImageListView, but I can't get the customization I need from the class ImageListViewItem. I looked at the source code from Github for ImageListViewItem, and I thought I would be able to extend the class and add another constructor like this:

 class CustomizableImageListViewItem : ImageListViewItem
{
    public CustomizableImageListViewItem(Image image, string fakePath, string name)
    {
        mZOrder = 0;
        Guid = Guid.NewGuid();
        ImageListView = null;
        

and there's about 15 more variables

This is part of the library I am trying to extend

public class ImageListViewItem : ICloneable
{
     #region Member Variables
     private int mZOrder;
     private string mText;
     private Guid mGuid;
     internal ImageListView mImageListView;

and like the previous example theres a lot more of these, I made sure to include the ones I was trying to use before

I get errors about how most of the variables don't exist in the current context. Why is this and is there any way to fix it?