Real simple.
Get two things happening - upload and MP3 file reading:
1) A file upload to the server (aspupload or whatever)
2) Read the file in the upload component and save it to disk
3) Use the script MorningZ posted to access all the information
4) Do whatever you like from that point
For the upload version, you can use aspupload or Dundas Upload or the SoftArtisans component or whatever you like.
If you like free, go for Dundas. If you think you might need support, go for a commercial component.
Your pages should follow a simple path:
1) Page 1 allows users to upload mp3s
2) Page 2 accepts the upload, saves the file, perhaps does some database work or other file system work and returns a result
Mart, for your question about the component posting... just check the documentation for a component. It will tell you exactly how to handle the file once you receive it on the "post to" page. And yes, when you click submit, the file upload BEGINS.
I hope that helps clarify - looks like there's a bit of confusion in this thread...
Cheers