How to make local coordinate coincide with global coordinate?

I just create an object, but I have trouble to move/rotate it to make one face to coincide with the xy plane. Please help. Thanks!

Welcome to the forums! Can you explain your question a little more? What are you trying to accomplish with this move rotate?

Sorry for my bad English, but I just created pyramid and I want to one of the faces exactly put one the floor (the XY-plane). And make the center of that face locate in the center of XY-plane. Currently the pyramid is in the blender space at random position.

Thanks!

you can orient the face with the xy plane, but why not create the pyramid on the xy plane from the start