Tell you the truth, an F wouldn't look so good when applying for grad schools. A lot of it depends though--is this class for your major? An F in a class for your major is much worse in terms of getting into grad school. Is this your only F? More than one F on your transcript=definitely not a good sign.
There are things you can do about this though. You think you could possibly withdrawal from the class and take a W? A W on a transcript looks MUCH better than an F. If worse gets to worst though, and you do get an F, you can always retake the course and get a better grade. Our school has a policy that if you get an F, retake the course, the F is completely replaced with the new grade.
Just remember that the semester is not anywhere near done. You can still recover your grade. Just find out what you have to do (like get a certain grade on these tests, papers, assignments). Also, try talking to the prof about your concerns. I know, sometimes it's hard (I myself get nervous talking to profs), but just sincerly tell him/her what's going on, and that you're open to any help. Good luck with this!