How can i change the file size of my mp3 from 4,500 kb to 900 kb??what kind of application do i need?

If you have an audio program like %26quot;Music match juke box%26quot; you can %26quot;recode%26quot; the MP3 to a lower quality bitrate to reduce size, but you WILL see a noticeable drop in quality from a 4.5mb file to a 0.9mb one.