Within the Library of your account you can create as many folders as you would like! When creating your folders, make sure to segment them to make it easy for you to find the files within your account. When creating folders, you can create subfolders as well, so If you are separating out your folders by the type of emails you send (i.e. Newsletter, Promotion, Holiday) you can have a folder for each type of campaign you send, then within those folders you can even narrow it down more by creating subfolders (i.e. Products, Services, Customers). If you want more information on how to add folders, take a look at this post.