How to open new page in new windows for nopCommerce

The file is _Root.Head.cshtml, the path is Nop.Web/View/Shared/ _Root.Head.cshtml, add before as below:
@using Nop.Core
@using Nop.Core.Domain.Common;
@using Nop.Core.Infrastructure;
@{
var displayMiniProfiler = CommonHelper.GetTrustLevel() >= AspNetHostingPermissionLevel.High &&
    EngineContext.Current.Resolve<Nop.Core.Domain.StoreInformationSettings>().DisplayMiniProfilerInPublicStore;

//resources
Html.AppendCssFileParts("~/Content/jquery-ui-themes/smoothness/jquery-ui-1.10.3.custom.min.css");

Html.AppendScriptParts("~/Scripts/public.ajaxcart.js");
Html.AppendScriptParts("~/Scripts/public.common.js");
Html.AppendScriptParts("~/Scripts/jquery-migrate-1.2.1.min.js");
Html.AppendScriptParts("~/Scripts/jquery-ui-1.10.3.custom.min.js");
Html.AppendScriptParts("~/Scripts/jquery.validate.unobtrusive.min.js");
Html.AppendScriptParts("~/Scripts/jquery.validate.min.js");
Html.AppendScriptParts("~/Scripts/jquery-1.10.2.min.js");
//add pupop
Html.AppendScriptParts("~/Scripts/pupopTip.js");

//X-UA-Compatible tag
var commonSettings = EngineContext.Current.Resolve<CommonSettings>();
if (commonSettings.RenderXuaCompatible)
{
    Html.AppendHeadCustomParts(string.Format("<meta http-equiv=\"X-UA-Compatible\" content=\"{0}\"/>", commonSettings.XuaCompatibleValue));
}
}
<!DOCTYPE html>
<html @Html.Partial("LanguageAttributes")>
<head>
    <!-- Google Tag Manager -->
    <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
    new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
    j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
    'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
    })(window,document,'script','dataLayer','GTM-MT3JMK');</script>
    <!-- End Google Tag Manager -->
<title>@Html.NopTitle(true)</title>
<meta http-equiv="Content-type" content="text/html;charset=UTF-8" />
<meta name="description" content="@(Html.NopMetaDescription())" />
<meta name="keywords" content="@(Html.NopMetaKeywords())" />
<meta name="generator" content="nopCommerce" />
<meta name="google-site-verification" content="YcdHXMIdUFkSueRbht63U4qY-BRV4JiU_p3otFwEd50" />
@Html.NopHeadCustom()
@*This is used so that themes can inject content into the header*@
@Html.Partial("Head")
@Html.Widget("head_html_tag")
@Html.NopCssFiles(this.Url, ResourceLocation.Head)
@Html.NopScripts(this.Url, ResourceLocation.Head)
@Html.NopCanonicalUrls()
@Html.Action("RssHeaderLink", "News")
@Html.Action("RssHeaderLink", "Blog")
@*Favicon - upload favicon.ico file to the root directory*@
@Html.Action("Favicon", "Common")
@if (displayMiniProfiler)
{
    @StackExchange.Profiling.MiniProfiler.RenderIncludes()
}
<!--Powered by nopCommerce - http://www.nopCommerce.com-->
<!--Copyright (c) 2008-2013-->
<base target="_blank">
</head>
<body>
<!-- Google Tag Manager (noscript) -->
<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-MT3JMK"
height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
<!-- End Google Tag Manager (noscript) -->
@RenderBody()
@Html.NopCssFiles(this.Url, ResourceLocation.Foot)
@Html.NopScripts(this.Url, ResourceLocation.Foot)
</body>
</html>