The answer provided by akannan is excellent. I would like to say, however, that it is a very common mistake of young students to burden themselves with projects that are larger and more complicated than necessary. They then often fijnd themselves snowed under with research material and deadlines closing in. I don't believe that you should take on the task of comparing two works by William Blake with one by Lord Byron unless you absolutely have to. Less is more. You are only a freshman. I doubt if your thesis has to be much longer than about twenty pages. I suggest that you leave Bryon for some later occasion and simply compare Blake's Songs of Innocence with his Songs of Experience. I don't know what your thesis statement would be, but it seems obvious that you would quote several songs of innocence and several songs of experience and present your interpretations as well as others that might strike you in your research. No doubt you could find a good thesis statement while reading what others have had to say about Blake. The thesis statement comes first--but it doesn't have to be composed first! You can do a lot of writing before you hack out a thesis statement and then polish it until you are satisfied. If you are having trouble with a thesis statement, it might be because it would seem to be so very difficult to compare two different authors and three different works in just a few words.
I think that one potential connection between Byron's Manfred and Blake's Songs of Innocence and of Experience can be how the human predicament is poised between redemption and condemnation. To be human is to experience both realities. This is a dominant element in understanding both works. Manfred is one such reality. Part of the reason that the titular character in Byron's work is unable to find redemption is because he fails to acknowledge the spiritual reality that encompasses him. The condition in which Manfred comes to be is one in which the promise of redemption is blighted by reality that reflects lack of totality:
Sorrow is Knowledge: they who know the most Must mourn the deepest o'er the fatal truth,The Tree of Knowledge is not that of Life.
Manfred is one who cannot find any comfort in being in the world. His consciousness is marred by the pain of experience. Human endeavor to appropriate the world in accordance to one's own vision is filled with sorrow. Redemption is denied when one strays from a larger "tree of knowledge."
Blake's vision of the human predicament is similar. For Blake, the child's innocence represents hope and salvation, a path for individual redemption. In poems such as "The Lamb," the human being is saved when they embrace their part in a larger configuration. Similar to Manfred, when the individual moves away from this and into the world of experience, pain and suffering result. The vision of the world in "London" is one where condemnation is part of consciousness. Both Byron and Blake speak to a human condition where the opportunity for hope is present. Yet, human action is one that compels the individual to move away from it, a pivot that causes ceaseless pain and hurt as a part of being in the world.
Reflective of this condition is the idea that human subjectivity is a critical aspect of consciousness. Both Blake and Byron show a world where human emotion is critical to identity. Byron shows subjectivity as an essential component to the human experience. Emotion is not something to be overcome. Rather, it is the prism through which consciousness is interpreted:
The night Hath been to me a more familiar face Than that of man; and in her starry shade Of dim and solitary lovelinessI learned the language of another world.
The world Byron develops in Manfred is one in which the "language of another world" is understood through emotion. Emotions and subjectivity are essential to sensing the truth that is vital to human development. Blake emphasizes this same subjectivity. In "The Tyger," Blake uses emotions such as confusion and doubt to develop what it means to be a human being. In "The Shepherd," Blake uses the emotions of comfort and security to convey how the sheep feel towards the shepherd and how the human being can display such reciprocity towards the divine. The definition of human existence rests in the subjective experience. In both Blake and Byron, human subjectivity is incredibly important in the definition of modern consciousness.