Make sure you have mounted the dotlrn-ecommerce package.
OpenACS in general does not have a centralized administration feature. To administer a particular package you need to go to the pages provied by that package.
For exmaple
if you mounted dotlrn-ecommerce at "/dotlrn-ecommerce" you'd go to /dotlrn-ecommerce/admin/ to get to the administration pages. You'd see a link to admin at the url "/dotlrn-ecommerce/" if you had administrator privilege over that package.
