Note in the right menu bar on the home page there is a link to Help Contents.
From the homepage link, click to view the contents for the entire help file (including information on boolean searching, wild cards, etc).
From individual pages (for example. from your search results) clicking on the help link will take you to the Help files covering that page.
From any place in the database, simply click on New Search (in the right menu bar) to be brought back to the Home page.