Firstly your teacher may ask you to SHARE your site with them during the unit of work/assessment work. This is so that they can see how you are getting on prior to the assessment being due. Or you may be doing group work and need to add another student as an editor. To do either of these things, you need to ADD AN EDITOR. This first set of instructions shows you how to do this.
Secondly, your teacher may ask you to send them the link to your site (assignment). To do this you need to be sending them the URL to your site. These instructions are further below. These two things sound similar but are very different.