How to upload files from gridview Item template multiple row

Question

I have  gridview just like below i want to update all the rows whos are check i have done this but now i have added a template filed  with fileupload control and at the end after the gridview control i have a update button my all works are going fine before but when i include the fileupload control and on the click of the button Update my file  controls always shows nothing below is the line which read my file content 

" Dim fuploadFile As FileUpload = CType(grdSecurityQuestions.FindControl("FileUpload2"), FileUpload)"

it always shows nothing but when i use Upload button inside the template field then it save my file into my directory . but i want to save all the files at the end  by using the button at the end not usiing the button inside the template field of gridview below is the diagram of my grid.