You can soak it for 12 hours, then drain and put it in a cloth. Keep it moist so that it gets sprouts. This will take another 12 hours. Then dry roast it or dry in the shade in a hot place. Then powder it finely, sieve well.
If you get fine quality powder, that is best.
Take 2 or 3 spoons of powder, add water and make a smooth, watery paste. Then keep over slow flame and keep on stirring. This will start to cook and solidify. The color will change, you will know. A nice aroma will come. Take off from fire. Add a little ghee, jaggary taste. If you are feeding him semi solids you can add milk to it. Feed when warm to the baby. You can add a little boliled and mashed potato, carrot and other veggies the same way or with a little salt instead of jaggery