create a sharepoint online page based on custom template c#

Hi I have created a page template on SharePoint using this article https://petri.com/sharepoint-page-templates-have-finally-arrived-heres-how-to-use-them

Now I want to use it my c# code but I don't know-how

THANK YOU

using (var ctx = authMgr.GetSharePointOnlineAuthenticatedContextTenant(siteUrl, userName, password))
            {
                Web web = ctx.Web;
                ctx.Load(web.Lists);
                ctx.Load(web, w => w.SupportedUILanguageIds);
                ctx.Load(web);

                ctx.ExecuteQueryRetry();
                //Create the Page
                var page2 = ctx.Web.AddClientSidePage("PageWithSections.aspx",true);                  <------ STUCK HERE
                page2.AddSection(CanvasSectionTemplate.TwoColumnRight, 5);


                //page2.AddSection(CanvasSectionTemplate.TwoColumn, 10);
                page2.Save();