Hello mauicom,
There is of course no age restriction for using Linux. The file structure is a bit strange if you're used to Windows, but I've found the FreeBSD manual to be very good at learning the basic file structure.
Directory Structure Code:
/ Root directory of the file system.
/bin/ User utilities fundamental to both single-user and multi-user environments.
/boot/ Programs and configuration files used during operating system bootstrap.
/boot/defaults/ Default bootstrapping configuration files; see loader.conf(5).
/dev/ Device nodes; see intro(4).
/etc/ System configuration files and scripts.
/etc/defaults/ Default system configuration files; see rc(8).
/etc/mail/ Configuration files for mail transport agents such as sendmail(8).
/etc/namedb/ named configuration files; see named(8).
/etc/periodic/ Scripts that are run daily, weekly, and monthly, via cron(8); see periodic(8).
/etc/ppp/ ppp configuration files; see ppp(8).
/mnt/ Empty directory commonly used by system administrators as a temporary mount point.
/proc/ Process file system; see procfs(5), mount_procfs(8).
/rescue/ Statically linked programs for emergency recovery; see rescue(8).
/root/ Home directory for the root account.
/sbin/ System programs and administration utilities fundamental to both single-user and multi-user environments.
/tmp/ Temporary files. The contents of /tmp are usually NOT preserved across a system reboot. A memory-based file system is often mounted at /tmp. This can be automated using the tmpmfs-related variables of rc.conf(5) (or with an entry in /etc/fstab; see mdmfs(8)).
/usr/ The majority of user utilities and applications.
/usr/bin/ Common utilities, programming tools, and applications.
/usr/include/ Standard C include files.
/usr/lib/ Archive libraries.
/usr/libdata/ Miscellaneous utility data files.
/usr/libexec/ System daemons & system utilities (executed by other programs).
/usr/local/ Local executables, libraries, etc. Also used as the default destination for the FreeBSD ports framework. Within /usr/local, the general layout sketched out by hier(7) for /usr should be used. Exceptions are the man directory, which is directly under /usr/local rather than under /usr/local/share, and the ports documentation is in share/doc/port.
/usr/obj/ Architecture-specific target tree produced by building the /usr/src tree.
/usr/ports The FreeBSD Ports Collection (optional).
/usr/sbin/ System daemons & system utilities (executed by users).
/usr/share/ Architecture-independent files.
/usr/src/ BSD and/or local source files.
/usr/X11R6/ X11R6 distribution executables, libraries, etc (optional).
/var/ Multi-purpose log, temporary, transient, and spool files. A memory-based file system is sometimes mounted at /var. This can be automated using the varmfs-related variables of rc.conf(5) (or with an entry in /etc/fstab; see mdmfs(8)).
/var/log/ Miscellaneous system log files.
/var/mail/ User mailbox files.
/var/spool/ Miscellaneous printer and mail system spooling directories.
/var/tmp/ Temporary files. The files are usually preserved across a system reboot, unless /var is a memory-based file system.
/var/yp NIS maps.
Although some of this might be different to Linux it would look something like this anyway.
Your Home directory is where you store everything (aka My Documents). Extra partitions don't show as other harddrives on Linux but rather as just another directory that's mounted. For example if you have a 40gb partition for "Data" then it could be mounted at /mnt/data or /home/username/data or any other place for that matter.
Good luck!