Configuring User Avatar Settings
This plugin comes with an option to either use Gravatars or Custom User Avatar Uploads for user profile pictures. You can manage User Avatar type under CSSJockey >> Membership Modules >> Configuration >> Basic Configuration
You can also specify allowed file types here.
Enable User Avatars on Registration and Edit Profile Forms
You can choose to enable or disable User Avatar field while customizing the form fields. Please refer to Customize Form Fields for more details.