Hi, I'm Rodrigo and I will help you.
In this case, the best feature to use is the contact list.
On People, select "New contact"> "New contact list" and create the list you want.
To add the contacts to a list, right-click the contact > Add to list > select the list you created.
Unfortunately, you have to add the contacts to the list one by one, but once added to the list, you just have to enter the contact list name in the "To" or "CC" field to insert all contacts.