This page describes a method for uploading a .zip file containing picture files. If you would like to upload a collection of a combination of different kinds of files and folders (including picture files) all at once to Blackboard, please also see How To Upload Many Files and Folders to Blackboard at Once.
You can upload many pictures to your Blackboard course site at one time by using the a "package file" - a .zip file on your computer which contains the pictures which Blackboard can "unzip" for you.
Direct link to video: http://screencast.com/t/jz1HeludO
(there is audio in this video so make sure your sound is enabled)