Moodle has an extensive built in help system. At the bottom of most pages there is a link to a Moodle Docs entry for that page. Next to many objects in Moodle you will find a Help Icon. Clicking on this will bring up contextual help and is very useful.
Moodle also has a large user community and extensive online documentation. Some of these links require you to sign up for a free account at moodle.org.