C# - Copy A Textbox Value From Form1 To Form2?

I have Form1 that has a textbox and a button. When user clicks the button in Form1, Form2 opens up with a label control that carries the value of textbox in Form1.

What i did is set the textbox modifier of Form1 to Public, but when i call the textbox name of Form1 in Form2, i get an error that says "The name "txtbx1" doesn't exist in the current context". I wonder why since i already set the modifier of txtbx1 to Public.

Quick Note: i tried to instantiate Form1 in Form2 as:

Form1 f1 = new Form1();

and then call

f1.txtbx1.text

The odd thing is Form1 could not be instantiated (not highlighting occurs). On the other hand if i do Form2 f2 = new Form2(); Form2 gets highlighted!

This is how i show Form2 from Form1:

SetSalary salForm = new SetSalary();
salForm.ShowDialog();

Note that SetSalary represents Form2.