If you created your account with the syncing option, Covve will synchronize with all the contacts on your phone. This way you only need to maintain one list of contacts, with changes in Covve being reflected on your phone and vice versa.
As such Covve doesn't support a direct import of contacts from a file.
If you have a list of contacts in an Excel spreadsheet or a .CSV file that you want to add to Covve, you can import the file to the contacts account syncing with your device (e.g. iCloud, Outlook, Google Contacts).
The contacts will show up in your device's address book and will then, be synced into Covve.
See here for help on how to import contacts in your Contacts account.