Across the bottom on the right-hand side, you will see the Learn label, where you will find links to the User's Guide, Wiki, Questions and Answers, and Mailing Lists. Below the links, Wireshark also lists what version you are running and whether or not you are receiving automatic updates.

Once you have either opened a packet capture or run a capture for analysis, you will most likely use one of the many menu choices. The following covers what is possible in the File menu.