step-by-step instructions on how to build Android apps with Unity. Please help.
Here’s the overview: http://unity3d.com/support/documentation/Manual/android-GettingStarted.html
But you are probably looking for this: Unity - Manual: Android environment setup
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.