You can view all the files that you own in Deltek Collaboration (the files that you have uploaded to Deltek Collaboration from the view. Click Files, then My Files in the list of view options at the top of the Files tab (to the right of your Home page Favorites). This will provide you with a view of all your files.
To see the storage space used by each of your files, click Sort on the right side of the page, then By size from the list of options that appears. The files will be sorted in order of biggest to smallest.