public varibel

Question

hi my firends
i have a web page.i want to define a varible that can use in all events in this form.
i write it such as below

partial class : System.Web.UI.Page

{

Tbl_List tb = new Tbl_sList();

{

 if (!page.ispostback)  tb.name="ajjj";

}

{

protected void btnSave_Click(object sender, EventArgs e)

{

response.write(tb.name);

}

}

once at first tb.name get value and when i click on btnsave this value is null.

How can i maintain value in this varible?

protected void Page_Load(object sender, EventArgs e)