Keep in mind that object ownership is not a simple topic. There are plenty of valid reasons for letting users own their own objects..I think anyway!
My preferred technique is to put anyone who will be creating objects in the dbowner role - that way SQL makes dbo the owner regardless of which login actually created it. If Im cleaning up after they have been created, then I just modify the object owner - which is what I recommend you do in this case.
For them to see the objects, you have will have to grant permissions for other users to see them, plus they will have to fully qualify the object, like this:
select * from barbie.table
There is plenty to learn and trip over without letting users own objects. Keep it simple for now - you may never find a reason to do anything else!