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 :