Across the top right of the page you will notice the following six headings:
<username> : This links to your user page where you can put information about yourself or store bits of information you want to remember.
Talk: This links to your discussion page, where people can leave messages for you.
Preferences: Allows you to change your personal site preferences. Here you can change your password, change the language you prefer for the wiki interface, or choose to have e-mail notifications when watched pages are changed.
Watchlist: A list of all pages that you are watching. Pages can be added to this list by clicking Watch at the top of the page.
Contributions: A list of all contributions you have made including edits, comments, new pages, etc.
Log out: Click this link to log out of your account.
You can hover your cursor over the tabs at the top of a page to see an explanation of what that tab does and to see the keyboard shortcut for that tab.