How to get Value from Gridview on Button Click

Question

Good Afternoon all,

 

This my code

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="Billno" CssClass="Grid" BackColor="White" BorderColor="#CCCCCC"
BorderStyle="None" BorderWidth="1px" CellPadding="3" AllowPaging="True" ShowHeaderWhenEmpty="True"
onpageindexchanging="GridView1_PageIndexChanging" Width="900px" >
<Columns>
<asp:TemplateField HeaderText = "Sl No.">
<ItemTemplate>
<asp:Label ID="lblRowNumber" Text='<%# Container.DataItemIndex + 1 %>' runat="server" />
ItemTemplate>
asp:TemplateField>
<asp:BoundField DataField="Empid" HeaderText="Emp Id" />
<asp:BoundField DataField="Billno" HeaderText="Bill No" />
<asp:BoundField DataField="Bdate" HeaderText="Bill Date" />
<asp:BoundField DataField="Amount" HeaderText="Amount" DataFormatString="{0:N2}" />
<asp:TemplateField HeaderText="Status">
<ItemTemplate>
<button id="btnNot" class="btn-danger" runat="server" title="Not paid" Visible='<%# Convert.ToInt32(Eval("Status")) == 1 ? true : false %>' causesvalidation="False"> <span class="fa fa-times " style="font-size: inherit;" >span> <%# Eval("Status").ToString() == "True" ? "Not Paid" : "Paid" %> button>
<button id="btnpay" class="btn-success" runat="server" title="paid" Visible='<%# Convert.ToInt32(Eval("Status")) == 1 ? false : true %>' causesvalidation="False"> <span class="fa fa-check " style="font-size: inherit;" >span> <%# Eval("Status").ToString() == "False" ? "Paid" : "Not Paid"%> button>
ItemTemplate>
asp:TemplateField>
Columns>
<EmptyDataTemplate>No Record AvailableEmptyDataTemplate>
<FooterStyle BackColor="White" ForeColor="#000066" />
<HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
<PagerSettings Mode="NumericFirstLast" />
<PagerStyle BackColor="#CCFFFF" ForeColor="#000066" HorizontalAlign="Center" />
<RowStyle ForeColor="#000066" />
<SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
<SortedAscendingCellStyle BackColor="#F1F1F1" />
<SortedAscendingHeaderStyle BackColor="#007DBB" />
<SortedDescendingCellStyle BackColor="#CAC9C9" />
<SortedDescendingHeaderStyle BackColor="#00547E" />
</asp:GridView>

when i click html button how to get the Billno from gridview

 

Please help me to how to write code

 

Thanks all