I own a microphone, but I do not understand how to record and submit a Text with Audio story.
There are several free recording programs available on the internet. I suggest one called Audacity. It allows you to record your story in its entirety. Once you have your story recorded, follow the instructions found in the site's FAQ
. I would suggest using the server upload option as the email option is not always fail-proof. Simply click on the "upload your file" link within those instructions and then click the same link on the following page.