Activating your course site means you're"publishing" it and making it accessible to enrolled students
Familiarize yourself with where to go when it's time to activate your course site
Click More Tools and select All Course Tools
Choose Course Offering Information
To "publish" your site choose the option to make it active
Click Save
Find your course from the My Courses widget
Notice that the course will have an "Inactive" label
Hover over the course and click the three dots
Choose the Course Offering Information option
Follow steps 3 + 4 above to activate your site
Students will be able to see any content you've made visible in the site (i.e., where you toggled the hidden/visible option when you made it) unless you have set a specific availability start date on that content, or a release condition. If you leave an item hidden students won't be able to see it.