Uploading a .CSV to a Campaigns requires a Premium or Enterprise level plan
Using the Salesforce Sync with Campaigns Campaigns requires an Enterprise level plan
Campaigns is available using either Gmail or O365
Reps and Managers can add recipients to their campaigns directly from within Salesforce using the “Add to Campaign” button on a list view, individual Contact or Lead page within Salesforce.com, or by uploading a CSV file of the recipient information.
Uploading a CSV once you've chosen a Campaign:
You can then choose a campaign to add the recipients to by clicking Use Campaign:
From there, you'll have the option to edit the content for each touch or preview & customize for each recipient: