The File Manager is what you use to Upload your Images, documents, spreadsheets, PDF's, Multimedia files, and other assets to your website. When you upload your assets - they are stored until you delete them. There is no need to worry about Folders, FTP accounts, or the like. It's completely built in.
Whenever you need to use an image or asset, you simply pull it from the File Manager. When you add a specific Block to your website, you can have that block contain whatever assets you want. It pulls the information from the File Manager. You can choose to display

Files within the File Manager can be sorted into different "Sets"
Example. You upload 15 images of cars. You can then add them to a file set called "Cars"
This allows you to ensure that all of your assets are sorted how you want them to be. And it also makes it easy for the website editor to display your content where you want it.
Other Facts
File Manager actually chooses where to put files on its own so it doesn't accidentally over-write anything, and it also creates records in your database about the assets so it can manage versions, permissions, and interesting meta data.

Within File Manager, you can "Edit" your Images. This will allow you to crop, cut, resize, or re-color your images so that they fit just the way you want them to.
Example. Uploading a 4MB Image may take awhile for visitors to load that image themselves. As such, you can go in and resize the image down to the exact size you need. The average storage per image averages 70KB, so you can see just how important it is to keep your image sizes down. There is no point in having a 1200x900 image load if it's being put into a box only 200x150.
