Parsing Data To Data Table Columns

I was given an assignment to parse out a text file, without a header record, using only a handful of the 300+ fields supplied. Since there is no header record to define the fields as in a CSV file, I was given these preliminary instructions after creating the HTML page using the file upload control and a few labels and such:

1- create a data table
2- add the columns I want to use to the table
3- save the uploaded file
4- define a stream reader
5- read each row and use MID to extract the data I need
6- write this data to the data table
7- display all the records in a grid view

I've managed to get to step #7 and that's where I'm having trouble. When I look at the data in the grid view, all the fields are in one column, the first column.

I had a little trouble earlier on and a colleague told me to concatenate the parsed fields using a comma and double quotes ("fld1","fld2","fld3"...) which sounded odd but I listened and now, I realize he was leading me down the wrong path.

So:

I used "Dim dtWork as New DataTable"
then "dtWork.Columns.Add("Lastname") for each column I wanted
then saved the file "Dim sPath As Sting="C:..."
defined a stream reader "Dim rdr As New StreamReader(sPath)
Read the rows "Dim sCurrentRow As String = rdr.ReadLine"
and parsed the data "Dim sLastName As String = Mid(sCurrentROw, 3, 25)"
did this for all my fields I wanted and then concatenated each field as described above into a string "Dim sData As String = sLastName & "," & sFirstName & ","....
and added it to the data table "dtWork.Rows.Add(sData)"

So that's the jist of it sans the datasource = dtWork and then the databind. Now, how do I get each parsed field into each respective column the right way?