Hi,
I am not sure what you are using?
Is it ASP.Net WebForms or MVC?
Anyways here is the solution.
Let's say you have a Session variable
Session["Name"] = "Mudassar";
Then you can display in HTML in following way
ASP.Net WebForms (ASPX Page)
<%=Session["Name"].ToString()%>
ASP.Net MVC (View)
@Session["Name"]
But if you want to access from plain HTML, then you need to do an AJAX call and access Session from Server