how to change the url of the page in asp.net

how to change the url of the page in asp.net

I am using asp.net and i have a hyperlink tag like this:
<asp:HyperLink ID="BusinessWebSiteHyperLink" runat="server"
Text="Hyperlink"></asp:HyperLink>
I am adding the address from code behind like this:
DataTable dt =
objYPSearchResultsDataAccess.GetYPBusinessListingDetails(businessID);
BusinessWebSiteHyperLink.Text = dt.Rows[0]["BusinessWebsite"].ToString();
string Hyperlink = dt.Rows[0]["Hyperlink"].ToString();
if (Hyperlink == "True")
{
BusinessWebSiteHyperLink.NavigateUrl = BusinessWebSiteHyperLink.Text;
}
else
{
BusinessWebSiteHyperLink.NavigateUrl = "";
}
every thing is fine but when i click the Business url in the page then the
page should redirect me to the business website but it is adding
localhost/7467567/...../www.stakeoverflow.com. i just want to redirect my
page to stakeoverflow when it is clicked. how to solve this?