It seems that both the $class and %db_info are getting put together.

This is exactly what happens. When you bless an object, you take a reference (in this case to a hash), and attach a classname to it (which can be easily retrieved with ref.) The reference with the attached classname is is the object. When you call a method on an object the object itself is passed as the first argument.

You may want to look closer at those examples you have seen, or look for better examples. (You might want to try perltoot or perlobj, if you haven't already.)