Hopefully is an adverb meaning "in a hopeful manner." It should not be used to mean "I hope" or "it is hoped," as in "Hopefully, Congress will decide not to enact the bill." In that sentence there is nothing for hopefully to modify. The only verb is decide and certainly the sentence is not meant to say that Congress will decide "in a hopeful manner." As another example, "Hopefully, she looked at the numbers on her lottery ticket" is not the same as "She looked hopefully at the numbers on her lottery ticket."