Why do you say you "cannot?" Are you clicking edit and getting forms and then getting some type of message telling you that you can't add that particular type of credit?
Basically, since the site is title driven, you'd start at the title's page. Then, you'd click the yellow "edit page" button and choose what type of data you're trying to add. If you have any specific questions, add them and we can see what it is you're doing and give advice.