First of all, go to the Server Reference Manual for a more detailed step by step guide on how to deply the server and mobile clients. Here you are a simple walkthrough.
You first instal and set up the server (it always and only is installed in a Windows server). Then, you can use either the iPhone app available in the iTunes App Store (which is very limited in regards to selections and the amount of information displayed at a time) or the browser which will render each sheet as you can see it (well, very similar to) the Web View in the QlikView Desktop application. To enable the webview open the document you want to use, go to Settings menu, Document Properties, General tab and click on "Use Web View in Layout". Save the document, close QlikView and open the document again. You can now work with a closer approach on what you are going to see in a web browser.
If you choose the iPhone app, you need to go to the server Console (Windows startup button, All programs, QlikView, QlikView Enterprise Management Console, Documents, click on the document you want to display on mobile, and under "AccessPoint Access Methods" click "Mobile Client" as well. Apply changes and it's done in the server part.
The iPhone app needs to be configured so it uses the DOMAIN\Username as returned by the function OSUser() in QlikView (you can use it in a new empty text object to check, then delete it) and the password this username has in the domain. For what it's worth, the iPhone app doesn't support section access. You need to configure the server name and port (if it's different to 80).