need to know about how to work with Template field of gridviw...

protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                var data = new List<Data>();
                data.Add(new Data { Id = 1, Name = "Abc" });
                data.Add(new Data { Id = 2, Name = "Abc2" });

                GridView1.DataSource = data;
                GridView1.DataBind();
            }
        }

        protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                var nameValue = (e.Row.FindControl("txtName") as TextBox).Text;
            }
        }

        protected void btnClick_Click(object sender, EventArgs e)
        {
            foreach (GridViewRow item in GridView1.Rows)
            {
                Response.Write("<br />Your value - " + (item.FindControl("txtName") as TextBox).Text);
            }
        }

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" OnRowDataBound="GridView1_RowDataBound">
    <Columns>
        <asp:TemplateField>
            <HeaderTemplate>
                Name
            </HeaderTemplate>
            <ItemTemplate>
                <asp:TextBox ID="txtName" runat="server" Text='<%#Eval("Name") %>' />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<asp:Button Text="Click" ID="btnClick" runat="server" OnClick="btnClick_Click" />