'Login' button is in top right of any page. You will need to login with UCLA Online ID (formerly BOL ID). If you have not logged in before, your account must be manually verified before you can do anything interesting. Once you've submitted your account verification , you'll normally hear back with 1 working day. More help at www.semel.ucla.edu/help/login .
If you have a verified user account, and you are listed as an 'Instructor' you should have an 'Edit' tab visible. If it is not visible, contact the Education office - they coordinate all course listings. On the course page, you can update the overview, add objectives and add material useful to students (web links, publications, upload files (PDF, Powerpoint etc) and embed slideshows). More details on editing the course pages are at www.semel.ucla.edu/help/content/training .
Note that the server builds a high performance cached mirror of the whole website every night, so your saved edits may not be visible to the public until the next day. If you want to confirm your changes, you are always viewing live data when you are logged in - which is why the website is usually slower due to the vast number of database queries needed to build a fresh page.