During this semester you need to choose a thesis/professional paper advisor. Since this is probably your most important decision as a Master's student, please spend some time and effort. Two major factors influence your choice of advisor.
Since you should have had more than a couple of the faculty as instructors by this semester, you will have some information on which to base your choice. Often, current grad students who are almost done are a great source of information on their (and possibly your future) advisor. Once you have chosen your advisor, you will need to do some original research to graduate. Start working.