please chek the follwing URL , it explain ExecuteScalar in detail.
http://vb.net-informations.com/ado.net-dataproviders/ado.net-executescalar-oledbcommand.htm
Srr
vb.net and excel formatting
you can see a detailed vb.net excel 2007 formating here , check this link
http://vb.net-informations.com/excel-2007/vb.net_excel_page_format.htm
http://vb.net-informations.com/excel-2007/vb.net_excel_2007_tutorials.htm