vb.net - open existing excel file using windows file dialog box and assign value to a cell

I'll show you two ways, first to create new workbook:

I'm assuming you've adding the com reference.

Private Sub btnExcel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExcel.Click
     RUN_EXCEL_FUNCTIONS()
End Sub

Private Sub RUN_EXCEL_FUCNTIONS()
     Dim xlApp as Excel.Application  
     Dim xlBook as Excel.Workbook
     Dim xlsheet as Excel.worksheet

     xlApp = Ctype(CreateObject("Excel.Application"), Excel.Application)
     xlBook = Ctype(xlApp.Workbooks.Add, Excel.workbook)
     xlsheet = Ctpye(xlbook.worksheet(1), excel.worksheet)

     xlsheet.application.visible = True
     
     'Insert the Data from the form here
     xlsheet.cells(1,1) = "First Cell"
     and so on.....
     
     'Save the sheet
     xlsheet.saveas("C:\.........")

     'Excel will be running and left open....

__________________________________________________________________________________________________
** Now to browse for a file, simple add a 'OpenFileDialog' to our form, name it 'browsefile' or whatever...have a textbox, and a button to call the browsefile object.
Private Sub btnBrowse(ByVal sender as System.object.........) handles btnbrowse.click
        browsefile.showdialog()
End Sub

'At this point you will be prompted with a Open File dialog box to search for the file.  
'Then go to the FileOK method of the browsefile dialog...you can do two things here, the openfile method or the following...I do things differently

Private Sub browsefile_FileOk(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles browsefile.FileOk
        Dim filename as string
        filename = browsefile.filename
        Systems.Diagnostics.Process.Start(filename)
End Sub
'The file is now open
'You can make your changes or insert data as needed.  Create function the sets the xls.activesheet or whatever you want, tons of option

xlapp.workbooks(1).activate <-activates the first sheet

Your question wasn't very clear as to what you wanted to do once the excel file was open...but you can modify cell or insert values into cells, using  Excel Application Object functions used above.  

Check this site out:  http://msdn.microsoft.com/office/understanding/excel/default.aspx

Hi:  Thanks for your help, but I'm still stuck.

I understand everything up until the solid line.  Starting with the ** and down 5 lines must leave out some steps that I don't automatically understand.  

I've added a new form called browsefile.

I've placed a button and text box on that form.

I've added the following code to the button click event:
     browsefile.showdialog() - the resuilt is a squiggly under the browsefile indicating something must have to be defined somewhere.

Can you offer further guidance?

Well, I was the only response, and it was a valid response at that.  

Thanks.