Forcing a page name in a URL

Not sure the right terminology here…

When a user goes to:

I need it to resolve to:

This is because a WordPress plugin I use only works if the page name is part of the URL.

DreamHost support tells me that I need to do this through my .htaccess file. I have modified .htaccess before and generally know how to edit it, but I need someone to tell me explicitly what I need to add. This is not my area of expertise.

Thank you!