Unfortunately, the free version of WordPress will not let you upload an audio file directly to your blog. But you can put your audio file on another Web site and then embed the link into your blog. Here is how to do it.1. Record and edit your audio file.
2. Make sure it is saved as .mp3 file.
3. Upload your file to an MP3 hosting Web site (or your own site if you have one).
Some free options:
4. Get the url of where your file.
5. Go to WordPress.
6. Write a post.
7. Make sure you use the HTML tab.
8. In your post write with the address inside like this: [audio http://wpcom.files.wordpress.com/2007/01/mattmullenweg-interview.mp3%5D
9. Save. Publish.
10. It will create a player on your blog that looks like this:
For more, see How do I get audio on my WordPress blog?