Molecular dynamics simulations have been used to study the effects of the corrugation in the holding potential of nitrogen molecules on the structure of fluid monolayer and submonolayer films of the molecules on a solid substrate. Structures of monolayer and submonolayer fluid films of nitrogen molecules adsorbed on graphite and on a model uncorrugated "smooth" graphite surface are compared. For films on the "smooth" graphite surface the melting temperature is lowered by 7 K. Contrary to what is found for films on the corrugated surface, the simulations show that there is a region of liquid-gas coexistence, demonstrating that this is a normal triple point system. A discrepancy between calculated and experimental melting temperatures of submonolayer films was traced to the intermolecular potentials. These have been tested by comparing molecular dynamics simulations of isosteric heats of adsorption in fluid films with experimental measurements. The establishment of the effects of the corrugation in the holding potential on the structure provides a basis for the study of the effects on the dynamical excitations in the films.