how can i do it between two linux machines

i need a ftp program, but do i need to modify something in some file or what??

Ftp server and client are installed with linux. Server is usually running if u have not shut in down.

Just type 'ftp <ip addr>' and it will do the thing.

If u have RH then there is a graphical ftp client named 'gftp'.

i need to create different kind of users for a ftp service with its permissions

how can i do that???

Not sure what you are asking...

You need an FTP server (something like vsftp OR proftpd) on the one box (or both for transfer back and forth) and a client (almost all modern distros have a command line FTP client installed by default).

To find out if you've got an ftp server running, use ps aux from a command line:
ps aux | grep ftp

It should bring up any instance of "ftp" that you have. If something is returned, then more than likely you've got the server running.

Next is to define IP's to host names (also known as resolving or DNS). This is done in your /etc/hosts file, the entry might look something like this (depending on the names of your boxes and their IP's):
192.168.1.25 cooler.localhost cooler
192.168.1.26 cool.localhost cool

This will resolve that name to that IP so you can just type names in, then:
ftp cool

Will start the ftp client into cool (Cool must be running a server, see above).

HTH

Cool