Also you may do the following :
String path = Server.MapPath("~\\App_Data\\Ooohh.xml");
if (File.Exists(path))
{
DataSet ds = new DataSet();
ds.ReadXml(path);
GridView1.DataSource = ds;
GridView1.DataBind();
ds.Dispose();
}
In this case the XML is read as a table and shown in the GridView1. Not sure what you mean by "store the read value in string variable".