Access properties in a different class

[MrGibbage]

Let's say I have this code:

using this;
using that;

namespace myNamespace
{
  public partial class Form1 : Form
  {
    public string myString;

    public Form1()
    {
      InitializeComponent();
    }
    
    private void SetButton_Click(object sender, EventArgs e)
    {
      MyOtherClass.TryToAccessMyString()
    }
  }
}

And then in MyOtherClass...

public class MyOtherClass
{
  internal static void TryToAccessMyString()
  {
    string testString = myNamespace.Form1.myString; //doesn't work
  }
}

Isn't there a way to access myString without passing it as an argument? It's been ten+ years since I have taken a programming class, so I am a little rusty. Please go easy on me. What is this concept called that I am trying to do (or break?) I'd be happy to just read up on it but I don't even know what to look up.

Thanks in advance.

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