Flickr Imagefield depends upon and enhances ImageField. You must first know how to use ImageField in order to use Flickr ImageField. It also uses the settings from the Flickr module so this module is required as well.
This module modifies the administration page of the Flickr module, providing help on how to get the required token that is needed for write access for your Flickr API key.
ImageField designation of Flickr upload
After setting up Flickr and creating your typical ImageField through CCK, you will notice a new checkbox while configuring your CCK ImageField in the Global settings, just above the Required checkbox. This checkbox will only be enabled if you have filled out your Flickr API information.
After enabling this checkbox your images will be uploaded to Flickr upon submission of new content that utilizes this field.