The Android Sdk separates tools, platforms, and other components into packages you can download using the Android SDK Manager. The original SDK package you've downloaded includes only the SDK Tools. To develop an Android app, you also need to download at least one Android platform and the latest SDK Platform-tools.
Launch the SDK Manager. If you've used the Windows installer to install the SDK tools, you should already have the Android SDK Manager open. Otherwise, you can launch the Android SDK Manager in one of the following ways:
On Windows, double-click the SDK Manager.exe file at the root of the Android SDK directory.
On Mac or Linux, open a terminal and navigate to the tools/directory in the Android SDK, then execute Android SDK.
The SDK Manager shows all the SDK packages available for you to add to your Android SDK. As a minimum configuration for your SDK, we recommend you install the following:
The latest Tools packages (check the Tools folder).
The latest version of Android (check the first Android folder).
The Android Support Library (open the Extras folder and check Android Support Library).
Once you've chosen your packages, click Install. The Android SDK Manager installs the selected packages into your Android SDK environment.
With these packages installed, you're ready to start developing. To get started, read Building Your First App.
Figure 1. The Android SDK Manager shows the SDK packages that are available, already installed, or for which an update is available.
For more information about using the SDK Manager and some of the available packages, see the SDK Manager document.
This web site provides all information you need to develop Android apps, including design guidelines, developer training, API reference, and information about how you can distribute your app. We recommend you begin by reading Building Your First App.
For additional resources about developing and distributing your app, see the Developer Support Resources.