hi ,
i want to make the wifi shield as a router , make a network , and with this network i can control it by visual basic
if anyone have idea please tell me 
Is network code perhaps a bit big for some Arduinos?
Do you really mean a router, or do you mean an access point? I think it would be quite challenging to fit the functionality of a router on an Arduino.
I can't guess what "with this network i can control it by visual basic" means.
see i made a program that can control a wired arduino , but what i want is wireless , so i want to make my wireless shield as a wireless network , so my pc can connect to it , and send commands to it or program it
If your PC has a wireless adapter then you would usually have a wireless access point for it to connect to. In that case, just connect your Arduino + WiFi shield up to the same access point, et voila your PC and Arduino are networked. Then you need to provide a way to communicate over the network. The best way to do that will depend what you're trying to achieve, but for example if your PC is going to send commands to the Arduino then it might make sense to implement a web server on the Arduino and generate HTTP requests from the PC. You could even generate the HTTP requests from within a "visual basic" application if you want, although there are plenty of other ways to do it.
Once you have the shield connected to the PC there should be almost no change to your 'wired' program, just the serial source. On the PC side is where the most changes will be.