<p>I was wondering how i can force a user who has requested a page using Http to use the secure https version?</p>

<p>I am using Websphere 6.1 as my application server and Rad 7 as my development environment</p>

<p>Thanks
Damien</p>

Websphere is not a complete http server. It does have 'Transport Chains', which act like an HTTP Server.
Normally you will put a HTTP server in front. IBM provides IHS (IBM HTTP Server) which is a lightly modified Apache HTTP Server. The HTTP Server is configured with the httpd.conf file. There you add redirects in such a way that request for http are redirected to https.
Maybe you can give some detailed information about your infrastructure.