Write Your First Android App with Eclipse

In this tutorial, you'll develop a basic app for Android 4.0, aka Ice Cream Sandwich. You'll also learn how to modify the XML to add different types of buttons to your app. Finally, we'll move onto something more complicated: creating a clock widget and altering the location where this widget appears on the home screen.
To follow this tutorial, you'll need to install some software. The great thing about developing for Android is that everything you need can be downloaded for free:

• Eclipse (if you're new to Eclipse, the Eclipse Classic package is recommended)
• Android SDK
• The ADT Plugin for Eclipse (this can be downloaded through Eclipse's Update Manager. If you're new to Eclipse, the Android Developers website has all the information you need to add ADT to your Eclipse installation)

http://www.developer.com/ws/android/programming/adt-plugin-write-your-first-android-app-with-eclipse.html