Most Android phones have mobile versions of Gmail, Calendar, Contacts, and Google Talk pre-installed. You can download other mobile apps like Docs for free from Android's Market. To begin using these apps, follow these steps to add the account to your phone.
You can also access your apps from your Android's browser app. Just point the browser to m.google.com, touch the app you want to use, and sign in to your Google Apps account.
Mobile apps overview
Here's a look at just a few of the apps you can use on your Android: