I am trying to distribute my application to some people for testing. I have installed it on my Desire directly from eclipse and it works fine.
To create an APK-file,
You can test the unsigned-apk only on Emulator. And as its step of application deployment and distribution, you should read this article atleast once, i suggest: http://developer.android.com/guide/publishing/app-signing.html.
For your question, you can find the below line in above article:
All applications must be signed. The system will not install an application that is not signed.
so you have to have signed-apk before the distribution of your application.
To generate Signed-apk of your application, there is a simple wizard procedure, click on File -> Export -> Android -> Export Android application.
