To share to specific people, enter their email address, then choose whether you want them to be able to edit, copy or view. This is important! The default is edit, but most times you only want the other person to be able to view your file. This ensures your file is not changed, and they can simply make a copy of it in their own drive if they want to edit it in any way.
If there are many people you want to share the file with, you may want to simply email them a link. Click "advanced" in the bottom right hand corner.
On the next screen, choose the change option. If you only want those that are logged into their GCSD account to access, choose the "Anyone at Georgetown County School District" option. If you want others to be able to access it with the link, like parents, choose the "Anyone with the link" option. **This is the option that I choose for ease of sharing and use.