Variable sharing between methods

Hi,
Im trying to use a variable from one method in another method of the same class.
Can anyone tell me how to do this?
ex...
protected void EmailButton_Click(object sender, EventArgs e)
  {    
     string EmailSelected = EmailAddressTxtBox.Text.ToLower();
  }

protected void UpdateRecordButton_Click1(object sender, EventArgs e)
  {
     string EmailFromEmailButtonClick = EmailSelected(From EmailButton_Click Method);
  }

Thanks...
David