all right thank you but the problem we don't have such devices in iraq that's why i was wondering but thank's again
Don't have what devices? You mentioned a modem and router, I mentioned a modem and router (well, and a PC, but obviously you need to use that modem + router w/ something). All I did was tell you how to connect them.
All I can think is maybe that modem can't be connected to the router because it's only a USB modem (cellular??) and needs to be plugged into the PC. Then you use ICS to share that USB modem?
If so, then you could connect the wireless router to the PC's other (presumably) wired network connection (WAN to LAN, respectively):