The "green armies" were uncoordinated, spontaneous uprisings of the rural peasantry and sometimes urban workers usually fed up with the fighting, confiscation of materials, and conscription of men by both the Whites and the Reds. Attempts to organize them or recruit their help was almost always a failure. Their aims, when they had any, were usually anarchistic, but they lacked the education to articulate their goals in such language. That's why they're not an army, but many armies, split up across provinces and mostly unrelated to each other.