There is a number of important things to know about the way files work in a UNIX environment, particularly if you are used to the way Windows handles files.
Firstly, it is important to note that filenames are case sensitive. This means that filename is not the same as Filename and FILENAME is different again. This may take some getting used to as in Windows, any of the names would refer to the same file.
All files have a number of attributes associated with them. To view these, you use the -l flag with the ls command like so:
$ ls -l
-rw-r--r-- 1 dez users 1928 Dec 24 15:59 wibble
The -rw-r--r-- section denotes the permissions of the file. The first indicates the type of file (- for normal, l for link, d for directory (folder)). The other nine are in three groups of three - user, group and world (or other). In each group the three characters represent the same properties: read, write and execute (r, w and x respectively). So in the example above, the user can read from and write to the file, members of the group can only read from it, as can others (i.e. anyone who isn't the user or in the group). Permissions can be altered using the chmod command.
User and Group
The following two columns specify the name of the user and group the file belongs to. The user will be the name you log in with (and you can see this by typing whoami); the group could be any of the groups of users that exists. To see which groups you are a member of, type groups. As a new user, you are likely to only be in the group "users" but you may be added to others if necessary. For example, if you were working on a team project, you might get a group set up for the members of the team, allowing you all to edit the files for the project while not allowing anyone else to. File ownership can be changed with the chown command, and file group with chgrp.
Size, Date and Filename
The last three columns show the size of the file in bytes, the date and time the file was last modified and the name of the file. There's not really much to be said about these. :-)