All new users start out in auto-update mode. In this update mode, the new contacts Evercontact finds for you are automatically saved to the "Evercontact" group in your Google Contacts. (You can also see these contacts on your dashboard.)
From there, you can switch to manual mode. In manual mode, you manage the contact updates Evercontact proposes by going to your dashboard regularly and deciding which contacts to save, ignore or blacklist.
To change from one update mode to the other, follow the steps outlined below.