Internal Table Error

Dear all

I need the first column of the internal table as a checkbox. Please give me the syntax to do that.

Itried like

types:begin of is_ty,

a type c as checkbox,

matnr type matnr,

end of is_ty.

But its throw an error in the first row...Please give me the correct syntax....i am not writing my internal table in the output.I am just passing it to a Container alv and i am not using any table controls...So please tell me how can we make a Checkbox in Container ALV......plz help

thanks