public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        MessageBox.Show(Library.Apps_txt.resultvalue);
  //I want to be able to call that in any form or class using this namespace
    }
}
public class Library
{
    public struct Apps_txt
    {
        public static String resultvalue { get { return "result value IS: "; } }
        public static String Pbexcept { get { return "Exception has raised."; } }
        //thousand of string.
        //...
        public static String mystring1000000 { get { return "my string 1000000"; } }
    }
}