I assume you are a registered apple dev. Go to the developer portal, set up your devices certificates profiles etc. and download them to you computer. Then, with your iPod/Iphone, in XCode, go to the organizer and under your iphone, add the provisioning profile to your app.
In Unity, you have to go the Edit/ Settings/ Player and change the bundle identifier to whatever your's is. ex. com.PeterG.PetersApp. or, more generically, com.company.appName. Then you should be able to build your app. If it still gives you the problem, go to the target settings in xCode and change the bundle identifier there also.