In order to test your mobile site design, you can upload it to the server, then find a mobile device, or preferably, several types of mobile devices, go to the browser on that device.
But that’s a bit tedious. Here’s another way. Use an emulator. For instance, you could use the responsinator.com emulator, or you could use this one: http://www.mobilephoneemulator.com, or you could go to the App Store, and download an emulator app, like this one, called iPhoney, or like this one from Opera: https://itunes.apple.com/us/app/opera-mobile-emulator/id515290645?mt=12
But for the serious minded among you, there is a built-by-apple emulator. It’s inside a program called Xcode, which you can download from the app store. It’s not straightforward, though. So if you are interested in having the best emulator for iOS devices, try it. Here are instructions:
http://www.macinstruct.com/node/494
The most important thing is to test your design before you finalize it.