Step 1

(Add the following code to your Default.aspx page)

Take a gridview and take a checkbox as a templatefield and take a button:

<div>
<asp:GridView ID="GridView1" runat="server" AllowPaging="True"
 AutoGenerateColumns="False" CellPadding="4">
 <RowStyle BackColor="Beige" ForeColor="#333333" HorizontalAlign="Center" Font-Bold="true"/>

<Columns>
 <asp:TemplateField>
 <ItemTemplate>
 <asp:CheckBox ID="CheckBox1" runat="server"/>
 </ItemTemplate>
 </asp:TemplateField>
 <asp:BoundField DataField="TYPE" HeaderText="Type" />
 <asp:BoundField DataField="CHANNEL" HeaderText="Chanel" />
 <asp:BoundField DataField="CALLERID" HeaderText="Caller ID" />

<asp:BoundField DataField="RINGING_TIME" HeaderText="RingDuration" />
 <asp:BoundField DataField="DURATION" HeaderText="CallDuration" />
 </Columns>
 </asp:GridView></div>

// taking a button
<div>
<asp:Button ID="btn1" runat="server" Text="Play" onclick="btn1_Click"
/>
</div>

Step 2

Now finding which checkbox is checked by the following code on the click event of the button in Default.cs page.

protected void btn1_Click(object sender, EventArgs e)
{
foreach (GridViewRow item in GridView1.Rows)
{

if (item.RowType == DataControlRowType.DataRow)
{
CheckBox chk = (CheckBox)(item.Cells[0].FindControl("CheckBox1"));

if (chk.Checked)
{
//perform your task here
}
}
 }
}