Greetings!
Remain calm! The great thing about a research paper is that you can use others' criticisms rather than coming up with all the analysis on your own! You say you don't know where to start, but actually, you do: you read through everything. You'd be surprised how many people try to start writing without doing that. :-) Next, I would suggest that you note the highlights of each criticism. If possible, you might want to copy the selected highlights into a new document, to make, essentially, a list of the most important points. You can then decide what order you want to discuss those point in, and sketch a rough outline of the order of your paragraphs.
Often, when starting the writing itself feels like hitting a brick wall, the major obstacle seems to be "I have no idea what to write for a thesis statement!" If that's the case with you, skip it for now. Once you decide what points will be contained in your paper, you can then concentrate on summarizing the main focus into a cohesive thesis, in a sentence or two. Study the theses from the critiques you have, to see how other writers have stated them.
I hope this helps get you started!
Thanks,
Sarah, EssayForum.com
Sarah, EssayForum.com