when I render a scene for a human model I cant get the ground shadow to render,  what am I doing wrong?

use the command "display ground plane". set the model to cast shadows.

Thanks mate, I tried that but it still wont render, does final render have to be set all the way up I wonder?

May seem like dumb questions, but you do have Cast shadows check on in your
render settings, don't you?
If you are using Auto Settings go to Manual Settings and make sure.
And the light you want to cast a shadow has Shadows checked on.
Also if your lights are set to cast Ray Trace shadows make sure you have
Raytracing checked on in your render settings and have at least two
Raytrace bounces in your render settings.  One might be enough but
I like to make sure.
Another thing to check is to make sure the angle of your light is such
that it will cast a shadow.  Use the shadow camera for the light(s) that
is to cast the shadow(s) and make sure the light is pointing in
the right direction.  If not use the light's parameter dials to aim the light.

Ground shadow isn't real shadow. therefore it won't render under any circumstance.  Ground shadow is simply a mark on the Ground Plain indicating the geographical placement of the figure.  To get shadows to appear on the ground, you must click on Render in the menu bar, and click on options.  In the dialogue box that opens, check the checkbox for Cast Shadows.' 
Also, right click on your lights, and check properties.  For the light that you wish to cast ashadow, right click on the light, and check the properties.
Yours truly,
David P. Hoadley

Thanks guys, I will try that David, yes that ground shadow mark is very deceiving.

Looks Like I had ground plane turned off, cant have a shadow without a ground for it to be on.