What do you mean by "report" the releases?
You can report releases using the User CP. That's actually how the database here is updated; people report releases to us, then we release moderators verify that they actually exist then update the database.
Check it out here
I just know they exist because I read c 49->54 online
That must be the reason why they're not registered in the database. For a release to be recognized in MU it has to be announced via a website or forum and not merely uploaded to an online manga aggregate site.