Direct 3D is a feature supported or not by your graphics card. If you have a new and powerful GPU, then Direct 3D should be supported as long as the drivers for the card are installed. There isn't a way to install it. Install the latest drivers for your graphics card and then Direct 3D should be activated automatically.
Additionally, go to Start > Run > dxdiag and switch to the Display tab. Make sure to enable any setting if it appears to be disabled.