Currently, there isn't a feature available in Wowza to upload a file from your local computer to the server running your Wowza Streaming Engine.
In fact, you don't need a Wowza API to upload content to the server. You can use a web server running on the same machine as your Wowza installation and do an HTTP upload. You can either configure the Wowza content location to be the same as your web server root directory, or move the files from the upload location to your Wowza application storage directory.
Of course, you can develop your own custom HTTP provider that would enable this functionality. If you do need additional help creating this custom HTTP provider, I can send you a list of independent Wowza consultants that might be able to help you with the development phase. Also, you can post your project requirements in the "
Find a Consultant" forum section and ask for consultant help there as well.