tkaiser than you so much for your help!
after checking with dmesg and lsmod i found that the modules is loaded fine...
so i connected the board with a rooted android phone and from terminal emulator i tried the command lsusb and guess what: the phone detect the usb device as RNDIS/Ethernet Gadget!!!
after that i found three problems with my pc:
1st: for some reason if i have connected on the 2 front usb ports of my pc the orange pi board and my FTDI usb to serial adaper, only the second show up on device manager of windows...
2nd: on the /etc/network/interfaces file i must add the line allow-hotplug usb0. if not the device is not detected by windows...
3rd: the windows don't load the drivers automatically. i flowed the instructions from this page and everything is working fine now...
So after all its very easy:
1) Add the g_ether module to /etc/modules
2) Add the following config to /etc/network/interfaces :
allow-hotplug usb0 iface usb0 inet static address 169.254.1.1 netmask 255.255.0.0 pre-up /bin/sh -c 'echo 2 > /sys/bus/platform/devices/sunxi_usb_udc/otg_role'
3) Manual install the drivers for windows.
Now you can use putty or any other SSH client to connect to orange pi IP (in the above example 169.254.1.1)
Once again thanks for your help!!