Go to the Groups page
Create a new group
Click the Create New Group button in the top right corner.
Name the group and create it
Do not check the "Automatically find users who should join this group" option. Click the Create button after naming your group.
Go to Members page
Click the Members tab at the top of the page.
Add a member
Click the Add new member button.
Select user(s) to add from pop-up window
Click on the name of the user you want to add. It will then add the user and close the window. Repeat as many times as necessary to add all the people you'd like to add.
Note: This is the same process you will use when you want to add additional members.