Electrical, magnetoresistive, magnetic, and resonance properties of the partially crystallized films of sodium-doped lanthanum manganites are studied. The objects of investigation are the films fabricated by magnetron sputtering of a ceramic target with nominal composition La0.84Na0.16MnO3. The samples under investigation are deposited on alpha-Al2O3 polycrystalline substrates held at two different temperatures (300 degrees C for film 1 and 500 degrees C for film 2) and subjected to the same post-deposition heat treatment. As shown, both films are characterized by a wide temperature transitional region from a paramagnetic state to a ferromagnetic one, and parameters of the transitional region (position and width) are governed by substrate temperature. Based on the results of complex analysis of the data of magnetic resonance and magnetic measurements, the salient features of the processes of nucleation and development of ferromagnetic phase are determined.