Diva GIS is a free computer program for mapping and geographic data analysis (a geographic information system (GIS). With DIVA-GIS you can make maps of the world, or of a very small area, using, for example, state boundaries, rivers, a satellite image, and the locations of sites where an animal species was observed. This site also provides free spatial data for the whole world that you can use in DIVA-GIS or other programs. DIVA-GIS is particularly useful for mapping and analyzing biodiversity data, such as the distribution of species, or other 'point-distributions'.
The resources you need for DIVA GIS and learning to use it for environmental niche modeeling
Below are the downloads and links you will need.
DIVA GIS website: DIVA-GIS.org