The Rensselaer Computing System (RCS) uses AFS (formerly called the Andrew File System), and acts like most other UNIX file systems in that, unless you have specifically placed files in your /public or /public_html directory (both of which are automatically created for you within your computer account), other users cannot read or use your files. However, the system also makes it easier for you to share files with others, both on-campus and at other AFS sites. Basically, RCS gives you the authority to share your files with others -- or keep them secure from others -- by allowing you to group your files into directories and then granting specific kinds of access to those directories. For example, you can set up a directory so that others can only read the files in it, like your public directory, or you can set up a directory so that others can both read and edit the files in it.
If you are unfamiliar with using basic UNIX commands, such as cd and ls, you may find it helpful to refer to Memo RPI.113, Using the UNIX Platform on the Rensselaer Computing System (RCS).