If you just need to install it to a phone you can move the apk file to
the SD card and navigate to it using any of the file browser apps.
When you attempt to launch it from the file browser it should prompt
you to install the application. Thats the simplest way if you have the
application built. If you need to build the app with a specific key
signature then you'll need to follow the steps on
android.com
http://developer.android.com/guide/publishing/app-signing.html.
If you just need to test it on a phone set the phone debug (Home-
>(menu key) -> settings -> Applications -> Development -> check USB
debugging). Once USB debugging is enabled and your phone is connected
to your computer eclipse should give you the option to launch the
application on your phone. Eclipse will take care of the debug signing
and installation.