How to show Gridview row into textboxes and then how to update that value?

Hi all,
Can anyone give me code for below scenario

First I get data from table and show in the datagrid of asp.net
When i click the First row of GridView it must come to the textboxes
like this
Texbox1.Text=ganesh(name)
TextBox2.Text=21(age)
TextBox3.Text=MCA(degree)
with update also how to do that?