If you are using Google Drive you may have had reason to want to share a document with a group of people. I suggest creating a folder and sharing the folder with the group of people, but there are reasons you would just like to have a contact group.
Go to http://google.com/contacts to see your contact list. It will show you your circles as well.
On the left hand side towards the bottom is the option to create a “New Group…” Click on this option.
There are a lot of different types of groups you may want to create. One for your grade level team. One for your students. If you are differentiating for your class you may have need to share a Google document with a subset of your class. You may want to create a group of your parents.
Click on Group
At the top of the group is an icon of a man with a plus indicating you can add people to the group. Notice when you hover over the icon a help tip tells you that you are adding contacts to that particular group.
In the box that appears you can copy and paste the email addresses of everyone in your group. I usually obtain these by having said people fill out a Google Form. You can also type their email addresses in manually. You can use a comma and a spacebar after each email to allow you to enter multiple email addresses in at once.
Use in Gmail
Use in Google Docs
If you want to share a document with a group, click on the blue share button in the upper right hand corner of the document.
Edit the Group
Go back to http://google.com/contacts to add or remove people from the group. You can also right click on the group name on the left hand side to delete the group.