Hi,
As per your question, My understanding is:
You have a web page with items and each items have a button "Add to cart"(or Item itself is clickable to add in Cart).
and you need to add this item details (ItemName, ID, Price etc.) in to a grid...
For this,
you first need a datatable, and when user clicks on item, you have to add the details (that you want) in to DataTable.
Finally,
Set the Datatable as Gridview DataSource
And If you still have some doubt, then you can Develop using following Video:
http://www.youtube.com/watch?v=GtE4LAOnaGs[
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