Android Develop. Build and Run.

step-by-step instructions on how to build Android apps with Unity. Please Help.

I’ll just paste here what I pasted in your duplicate forum post:

Here’s the overview: http://unity3d.com/support/documentation/Manual/android-GettingStarted.html

But you are probably looking for this: http://unity3d.com/support/documentation/Manual/android-sdksetup.html

After you follow the SDK setup you just go to your Build Settings, switch to Android, and build like normal. It really couldn’t be any simpler than it is, but let me know if you have any more issues and I’ll help where I can.