You can achieve this by either (a) entering the additional information that you need displayed into the Mailing Address field in Setup => Step 1 (Details) or by (b) directly modifying the contact template: templates/about/contact.tpl
Please note that if you go with route (b), you'll need to apply your changes to the template each time you upgrade OJS. This can be done by saving a patch
that contains the diff
of the modified file relative to the stock version that ships with OJS.