What template are you using? Do you see any JavaScript errors?
In Rincewind, when you click on an image you should see the "Link settings" popup. If it isn't showing, I guess it's either your template, a plugin producing a JS error or probably just your cache. Try following these steps:
http://www.dokuwiki.org/faq:toolbar (If it is the JS or the cache, those will help. In case it's your template, it probably won't.)