Many people have already organised their Contacts into Groups. If so, then you can opt to select names from one of these groups. You might already have a Christmas Group, so you can import those names. This makes it much easier than selecting All Contacts and then scrolling or searching through all of the Contacts, looking for the names you want.
So either tap on a Group (if available) or tap All Contacts.
The next screen will display all of the names in that group (or All Contacts) apart from the ones that have already been added to your list (if any).