How to address a function?

{

      Public class Form1 : System.Windows.Forms.Form
      {
         .........
            private static void ConvIPtoLong (string strIP)

            {
               ...... // some code that compiles
            }
            public void button1_Clicked (Object sender, EventArgs e)
            {
               // al I want to do here is to use the function
               // (method) that I just defined: ConvIPtoLong
               // and I get an error no matter how I reference it
               this.ConvIPtoLong ("198.28.87.221")
               // the compiler cannot find it in the class Form1
            }
      }
}

I also tried to place a statement at the beginning of the class Form1:

private System.Windows.Forms.AccessibleObject convIPtoLong;

Then I get an error message pointing to the convIPtoLong function definition that this object has already been defined previously.

You see, I do not understand something very basic in C# and cannot go any further until it is resolved. Please, help.

Thanks.