I was wondering if the game could be played without instruction. I guess not.
Well to start the game, find a fairly empty section of the belt. Then press the green button and deploy the solar smelter. Move away a bit, press the green button again and deploy one or more miners. They are the orange spheres. The miners will begin to capture asteroids and tow them into parking positions to be mined. The miners will protect the smelter somewhat.
That's about as far as the game goes atm.