The Sage CRM Developer Program website has recently changed and the address dpp.sagecrm.com is being discontinued.
The equivalent link on the new website is https://community.sagecrm.com/blogs/hints_tips_and_tricks/archive/2008/11/20/how-do-i-put-calculated-or-derived-info-in-a-screen-s-top-content.aspx
Alternatively continue to the Sage CRM home page or the Sage CRM Partner Community home page.