You can record your erotic stories over the telephone. Call 0203 455 0156 and when prompted enter your User ID and Voicemail PIN. (Remember, when you've finished recording press the hash key and option 3 to save it.)
As it is a London number, normal call charges apply.
The other option is to record audio to your PC and then upload it. WAV format works best.
To upload your Audio, go here
click the + sign next to 'Upload Audio Recording' and enter the relevant details.