You can also get started by doing some of the talking yourself. In many cases, students will be interested in your method and approach to the subject. You can remove the focus from yourself by talking a little about the nature of your subject, its methods, and its history. This introduction can begin to dispel any simplistic or mistaken notions of the field that your students may have. If Penn has had an impact historically in your field, as it has in computer science for example, that could provide a beginning for discussion.
Many classes touch on issues in the news.
You could bring copies of a recent article to the first class meeting, ask the students what they know about the issue, and use it as a springboard for a general discussion. Explain how the course is set up. The more you can refer to a syllabus, the better off you will be. Note exam and assignment dates for your students, point out where the reading assignments are heaviest, make clear, if you can, what the major emphasis of each part of the course will be. Of course there will be questions about whether exams are cumulative, how long assignments will have to be, and other things you may not have considered.