on the click of button or any hyperlink
redirect to url http://ursite.com/redirect.aspx?url=http://fb.com
In the redirect.aspx page load write down the code
protected void Page_Load(object sender, EventArgs e)
{
if(Request.QueryString["url"]!=null)
{
Response.Redirect(Request.QueryString["url"].ToString());
}
}
hope it will help you...