As Shridhar Gowda says you need to use updatePanel control if you wish to refresh a part of page instead of reloading whole page.Here I am giving you a sample code.
In .aspx
<![CDATA[<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
CodeBehind="Default.aspx.cs" Inherits="WebApplicationUpdatePanel._Default" %>]]>
<asp:content id="HeaderContent" runat="server" contentplaceholderid="HeadContent" xmlns:asp="#unknown">
</asp:content>
<asp:content id="BodyContent" runat="server" contentplaceholderid="MainContent" xmlns:asp="#unknown">
<asp:scriptmanager id="ScriptManager1" runat="server">
</asp:scriptmanager>
<asp:updatepanel id="UpdatePanel1" runat="server">
<contenttemplate>
<asp:repeater id="Repeater1" runat="server">
<HeaderTemplate>
<table style="border:1px solid #0000FF; width:500px" cellpadding="0">
<tr style="background-color:#FF6600; color:#000000; font-size: large; font-weight: bold;">
<td>
ID
</td>
<td>
NAME
</td>
<td>
Roll
</td>
</tr>
</HeaderTemplate>
<itemtemplate>
<tr style="background-color:#EBEFF0">
<td>
<asp:label id="lblID" runat="server" text="<%#Eval("ID") %>" />
</td>
<td>
<asp:label id="lblName" runat="server" text="<%#Eval("Name") %>" />
</td>
<td>
<asp:label id="lblRoll" runat="server" text="<%#Eval("Roll") %>" />
</td>
<tr>
</tr></tr></itemtemplate>
<footertemplate>
</footertemplate></table>
</asp:repeater>
</contenttemplate>
<triggers>
<asp:asyncpostbacktrigger controlid="btnAdd" eventname="Click" />
</triggers>
</asp:updatepanel>
<h3>Entry</h3><br />
<asp:label id="lblmsg" runat="server" forecolor="Green"></asp:label>
Name<asp:textbox id="txtName" runat="server"></asp:textbox><br />
Roll<asp:textbox id="txtRoll" runat="server"></asp:textbox><br />
<asp:button id="btnAdd" runat="server" text="Add" onclick="btnAdd_Click" />
</asp:content>
In Code behind(.cs)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebApplicationUpdatePanel
{
public partial class _Default : System.Web.UI.Page
{
BooksDBEntities db = new BooksDBEntities();
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindToRepeater();
}
}
void BindToRepeater()
{
Repeater1.DataSource = db.Students.ToList();
Repeater1.DataBind();
}
protected void btnAdd_Click(object sender, EventArgs e)
{
if (txtName.Text != "" && txtRoll.Text != "")
{
string name = txtName.Text;
string roll = txtRoll.Text;
Student s = new Student();
s.Name = name;
s.Roll = roll;
db.Students.AddObject(s);
db.SaveChanges();
lblmsg.Text = "Successfully Updated!";
BindToRepeater();
}
}
}
}
Hope it helps.And have look in Microsoft's msdn following link
<a href="https://msdn.microsoft.com/en-us/library/bb399001%28v=vs.140%29.aspx">Introduction to the UpdatePanel Control</a>