Each app store guides you through the steps of how to upload a new app and there are quite a lot of steps involved! It could take another book to show you all the screenshots you have to wade through. Showing these screenshots here would not be so valuable mainly because of their large quantity, but also because the process changes from time to time. For example, Google changed the name of their service from Android Market to Google Play.
There is some similarity between what each of the stores asks you, so we'll look at what preparations you might need before heading off to the stores. When you are ready to proceed with the uploading, these are the pages you need to start with for the respective app stores:
iTunes Connect: https://itunesconnect.apple.com
Google Play: https://play.google.com/apps/publish/
Amazon Appstore: https://developer.amazon.com/home.html
Samsung Apps: https://seller.samsungapps.com/