How to install apk ( application ) file into your android phone

Through the Android Market

To install APK applications on your Android phone do the following:

1. Copy the APK file you want to install to your phone's memory card and insert the card into your Android phone.
2. Go to Android Market and search for the Apps Installer application.
3. Open it and click on the Install button.
4. After it is installed, just open it. It will show you all the APK files stored directly in the root directory of your memory card.
5. Just click on the application you want to install and it will be installed.

Using the Android SDK

There is one more method that can be used, you can install APK files into your phone using the Android SDK. Download the Android SDK.
First of all, install the Android SDK on your computer. You will also need to install the Android USB drivers to connect the SDK to your phone via USB. You can download it from here - http://dl.google.com/android/android_usb_windows.zip .
To install applications from other sources, you also need go to Settings -> Application Settings and enable Unknown Sources. Also go to Settings -> SD Card and Phone Storage -> Disable Use for USB Storage. You can enable it again later.
Next, just open Command Prompt and type: adb install path/file.apk
where path is the full path to the APK file and file is the name of the APK application file. Your application is now installed. This is all you need to do, now just open the application on your phone and use it.

Read more: http://www.brighthub.com/mobile/google-android/articles/37151.aspx#ixzz16q7NXNkw