Browser's caching

I made some private aspx web pages. These pages are accesible through a sophisticated login-logout system in order for me to know at any time who is online and other stuff.

Even when I am logging out this system and the user main pages normally are not supposed to be accessible anymore, the BACK/FORWARD buttons of IE can show up the private pages using its cache. By pressing REFRESH the system works ok and redirects the user to the login page again.

My questions are: How to disable the browser's caching option for a specific page, if we can do that (inside the application, not some option in each user's browser). Also, is it a good practice to disable this feature for private pages or not? By forcing the user to be always connected in order to have access, maybe is not a good idea cause these pages includes many text information and I dont know really if we must force a new connection to show already shown data.