To update your profile, you must visit the Edit Profile page. You can move through the different parts of your profile by clicking the tabs at the top of the page.
If someone is bothering or harassing you, blocking them is usually the best solution. Visit the Account Settings page to learn how to block people. If someone continues to harass you despite your efforts, you can report them here.
You can report spam, pornography, or any other inappropriate content here, or by clicking the "Report" link on the page containing the content you wish to report.