When I type commands in the terminal, I get an error - & ldquo; Order not found & rdquo;

gal-harths-iMac:~ galharth$ ruby -v
-bash: ruby: command not found
gal-harths-iMac:~ galharth$ open -e .bash_profile
-bash: open: command not found

what shoud i do?

my .bash_profile and .profile and .bashrc are empty, i need to write something in them?..

I suspect that you have something overriding your default path (like .bash_profile or .bashrc) open is a valid command on os x, for me man open returns

     open -- open files and directories

     open [-e] [-t] [-f] [-W] [-R] [-n] [-g] [-h] [-b bundle_identifier]
          [-a application] file ... [--args arg1 ...]

     The open command opens a file (or a directory or URL), just as if you had
     double-clicked the file's icon. If no application name is specified, the
     default application as determined via LaunchServices is used to open the
     specified files.....

Likewise it is possible ruby is installed but not on the path. My best guess would be to delete or rename your .bashrc and .bash_profile files and log off as that user and log back in, to reset your bash session.

To test if it is a user level issue, create a new account under system preferences -> accounts and then log in as that user, open a terminal and type ruby -v or man open, etc to see if you can do it on a default user account. If that works, it is most certainly some bash settings you have customized in your 'gal-harth' account.