Linking to a html file in a folder

Hi All,
I am building a widget – and I create a link that links to a .html file located in the plugins folder for the plugin.
If I then place a link on the website to this html page.
http://www.domain.com/wp-contents/plugins/myplugin/test.html

The trouble is wordpress tries to look for this file in its own pages and posts and doesnt find it so I get a 404 error.

need to create the url to the actual html page, or even better yet – opens my test page with the website wrapped around it.

Ideas – have googled for 2 hours now.

pete