Create an application-level variable and whenever a page is opened, increment the variable. This is a very low-tech approach which you should improve on.
Example:
Code:
Global.asa
----------
<SCRIPT Language="VBScript" RUNAT="Server">
Sub Application_OnStart ()
Application("NumUsers") = 0
End Sub
</SCRIPT>
Increment.asp
-------------
<%
'include this file in every page which you want to track
Application("NumUsers") = Application("NumUsers") + 1
%>
Normal.asp
----------
<%
Option Explicit
'this is one of your pages which you want to track users.
%>
<HTML>
<HEAD><TITLE>My Page</TITLE></HEAD>
<BODY>
<%
Response.write Application("NumUsers") & " have visited this page."
%>
</BODY>
</HTML>
Note that this will count every user to every page as one hit. So if a user looks at 5 pages, it will increment the total by 5, but it won't track each page separately. To do that, just make an array at the application level, and assign a number to each page you want to track. Then increment that cell of the array on the individual page.
Hope this helps.