Transfer value in griedview from datalist.

what you have tried?

you can go like, create one data table with column to store your data-list value selected by you. and add rows based on your image button click, like if i click on 1 item then add row with containing value of first item to your data table and so on.
then bind that data table to your grid so it will display content to grid what you have store in your data table.
you need to store that data table to your session or any thing else so you can globally access it's value. once if data table is created then only insert new rows to existing data table.
and for displaying total transfer value, you can simply count the rows from data table it will return row count.