To use it you need to have blendigo open, then select a mesh in your scene and enable subdivision. Indigo subdivision works the same as the subsurf modifier available in Blender. It can be useful to use Indigo's built in subdivision because the models in Blender can have a low polygon count that are faster to work with – yet you still get a high quality render.
Subdivision in Indigo can also helpful for getting smooth results on objects that have displacement mapping.
See Mesh Subdivision