Everything we have worked with so far, has been initially available as part of Moodle and we have not installed or enabled anything. However, in a new site, some of the modules, including Workshop, are not available from the start. As a teacher, you will not be able to access these hidden or installable modules yourself, unless you also have administrator access. The first thing you will need to do is contact your site admin and have them 'Show' the Workbook module. Once it is visible, we can begin working with it.
If you are the admin, you can go to the homepage and click on Modules|Activities|Manage activities, which will show a list of modules available. Workshop is one of them, and to make it visible, click on the closed-eye icon. Once this is done, Workshop will be available for use by going to the Activities drop-down menu on your course page and selecting it.