how to design it up to you.i am giving you basic idea. try like this (make changes in below code as per your requirements or adjustment):-
<style>
#divmaingrid
{
top: 10;
left: 10;
height: 60%;
width: 80%;
}
#divGrid
{
width: 100%;
height: 80%;
position: relative;
}
#divButton
{
width: 100%;
height: 20%;
position: relative;
}
</style>
<div id="divmaingrid">
<div id="divGrid">
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" Style="left: 500px;
margin-top: 23%; height: 105px; width: 590px; background-color: #ECE9D8;" HorizontalAlign="Center"
BorderColor="Maroon" ForeColor="#CC9900" />
</div>
<div id="divButton">
<asp:Button ID="Button3" runat="server" Font-Size="x-small" ForeColor="Black" BackColor="White"
CausesValidation="false" OnClick="cancel_click" Style="margin-left: 3%; margin-top: 0%;
margin-left: 3%; width: 100px; cursor: pointer; font-family: Arial; text-align: center;
height: 22px; font-size: large; font-weight: 600;" Text="CANCEL " />
</div>
</div>