Step 1: Enable "Unknown Sources" on device
On the device, go to Settings > Applications and enable Unknown Sources (on an Android 4.0 device, the setting is located in Settings > Security).
This will allow the installation of non-market applications.
Step 2: On the right hand side of the Designer Window of your app, click on "Package for Phone." Then select "Download to this Computer".
The process takes a few minutes, so be patient. Eventually, you will be prompted to save your (app name).apk file to your computer.
The (app name).apk contains all of the code and files necessary to install and run your app.
Step 3: You can now email your app or transfer it to your device.
Clicking on the .apk file will install it and it should be able to run. If you have transferred the .apk file to a SD card, it might require an additional app to install it (such as App Installer)