If it is a molecule, you may create a XYZ file format. The 'xyz' format consists of:
<number of atoms>
comment line
atom_symbol-1 x-coord1 y-coord1 z-coord1
atom_symbol-2 x-coord2 y-coord1 z-coord2
...
atom_symbol-n x-coordn y-coordn z-coordn
The details can be found here:
http://openbabel.org/wiki/XYZ_(format) An example for methane molecule:
5
methane molecule (comment)
C 0.000000 0.000000 0.000000
H 0.000000 0.000000 1.089000
H 1.026719 0.000000 -0.363000
H -0.513360 -0.889165 -0.363000
H -0.513360 0.889165 -0.363000
The coordinates of all atoms must be given by cartesian coordinates (in Ångströms) . After preparing the XYZ file format for your molecule, you may import it into VNL by the "Result Browser" module and then visualize it by the "Nanoscope" module.
If it is a bulk system, you should also know the lattice parameters and lattice type. The crystal structure of a bulk can be created and visualized by the "Bulk Builder" module of VNL.