To share a doc, select the large blue SHARE button on the top right hand side of the page.
If you are wanting to share your doc with a wider audience and do not want to type in all of their email addresses, then try this option:
Restricted means that only people you add with their email address can access your doc.
Your school name means that anyone with the same domain name e.g. dunstan.school.nz can view your doc if you share the link with them
Anyone with the link means you can share the link to anyone (including people without an email address within your school domain... anyone!)
Make sure you click Done to save your sharing settings.
Copy link allows you to copy the link and share it with others e.g. through Gmail, Google Classroom...