I know nothing about Dreamweaver; I use Front Page, and its simple with that programme. I am sure a Dreamweaver enthusiast will tell you.
In the mean time you need something like this in your code in the head at the start of the page:
<title>My music page</title>
(Where your midi file is called music.mid). Ensure that the midi file is in the same directory as the rest of the page.
Mp3 files are certainly better quality, but usually a very large and take ages to download. In contrast midi files are very small. You can find hundreds of midi files on the web.
The quality of them varies, but some a really good.
Have a listen; its only 37kb.