In 3-tier architecture, populate textboxes from database

Question

Hi Friends, Can anyone help me with this? How to fetch data directly from database table to textboxes when I clicked on edit button in grid view,using 3 tier architecture? I have a table in SQL server database.Upon clicking on edit in grid view, the text boxes must be filled with respective values from database table.I have used sqldatareader, but values are not binding.Any suggestions would be helpful. Thank u.