how to edit and update image in asp.net

i want to know how to update image in asp.net and saved in database.I am new in dot.net
here,this is my query,
string qry; Stream fs = fu1.PostedFile.InputStream; BinaryReader br = new BinaryReader(fs); Byte[] bytes = br.ReadBytes((Int32)fs.Length);
qry = "update erp_Addbook set erptitle='" + txt_Title.Text + "',erpauthor='" + ddl_Author.SelectedItem.ToString() + "',erppublication='" + ddl_Publication.SelectedItem.ToString() + "',erpcategory='" + ddl_Category.SelectedItem.ToString() + "' ,erpcopyright='" + txt_Copyright.Text + "',erpedition='" + txt_Edition.Text + "',erpnumberofpages='" + txt_Noofpages.Text + "',erpISBN='" + txt_Isbn.Text + "',erpcost='" + txt_Cost.Text + "',erpdateofentry='" + txt_Dateofentry.Text + "',erplibrarytype='" + txt_librar ...