Your question looks suspiciously like an XY Problem, since it's very unclear what you ultimately hope to accomplish by registering the functions (which are actually class methods). (Also see What is the XY problem?) Nevertheless, here's one way to do what you want — assuming I understand what you have so far in your question.
I made Container.myRegister() a classmethod since it only references an attribute of the class it is in. I also defined the Container class before the Foo class so the former could be referenced by the decorator. In addition I removed the registerAll() method, since it's no longer needed (however that means the class attribute results is now not referenced anywhere, so maybe it should be removed, too...).