ok i have dx 10 gpu and acording to the unity docs a dx10 gpu can run dx11 in unity http://docs.unity3d.com/Documentation/Manual/DirectX11.html
how can i get it to work with my pc
it literally says right there. enable dx11 in the player settings and re-open the project.
however, don’t expect all dx11 features to work on an environment that doesnt truly support it. (i know, it makes much sense 
)