Project Files allows you to store small files, such as documents or source code.  Files can be no greater than 1 Mb in size at the moment.  If you need to store anything larger, than you can use the Links feature in combination with Amazon S3 or Dropbox to store your files.  The limitation is temporary and we are working on ways to allow larger files.

To upload a file, go to the Files section under the More tab.  Click the "Add a File" button at the bottom of the listing.  The file will be uploaded and the name of the file will appear in the listing.  Click the filename to download the file again.

The available space for your account will update to reflect any usage.  Your usage is for all projects, not per project.