Adding individual existing contacts to a list:
Start by opening the profile of the contact you wish to add
Click on the phone number of the contact to open the contact information screen. Then click Edit at the top right.
Once there, simply type the name of the contact group to which you wish to add this contact in the "Lists" field:
You can enter more than one contact list name if you want this contact to be assigned to multiple groups.
Adding contacts to a list in bulk
You can use the Import Contacts function to add multiple contacts to a list at once - even if the contacts already exist in your contact list. So long as you have duplication switched off, re-importing an existing contact will not create a duplicate record. To do this, you will first need to have your contacts saved in a .csv or .xls file.
First, open the contact list you want to add contacts to.
Then, click on Import
In the following screen, you'll see that the List field is populated with the current list name. You can add additional existing lists to this field if you want to add all these contacts to more lists:
Now just add the file containing your contact data and follow the process for importing contacts (click to view the instructions for importing contacts).
Removing Contacts from a List
Delete the list name from the contact information, by going to Contacts, then All contacts, then searching for the contact you wish to remove and then click the edit button at the top right. Then click on the cross next to the relevant list in the List field in the contact profile:
IMPORTANT NOTE: Clicking "X" will not delete the contacts from the main All Contacts list - just from this specific list. Be careful not to click "Delete" as this option WILL delete the contacts from the main contact list!