<quoted from other web>
You need to create Release Key for Signing your Application.
Step : 1 Right Click Project->Export Application->Select you Project->Next->Select new Keystore -> Complete all rest Steps
Step : 2 Note down your Alias name and Password given.
Step : 3 Now if you Complete all process of Filling Details you will get one .apk file and keystore file in you stored location.
Step : 4 Now Again Right Click Project->Export Application->Select you Project->Next->Use Existing Keystore -> Give location and password->Next
Step : 5 Now you alias name will comes in your Drop Down->Select it -> Enter Password -> Next
Step : 6 It will ask for location to store your final .apk file.
Step : 7 Select your location and store.
Step : 8 Now this Final .apk file is Your Signed Application.
Note : Keep this keystore file for further updated of your Application in Android Market ,also keep track of your Alias name and Password