Thank you for your query on Healthcare Magic.
You did right thing only.
From 6 months onwards lactogen 2 has to be started if you are giving formula milk to your child.
In addition to lactogen-2, from 6 months onwards you can give infant semisolid food like home made or commercially available like stage-1 cerelac.
Don't worry regarding the green stool
color as the color variation is normal in infants.
As the child is happy and active, there is no need to be panic.
But any new food is to be introduced in small quantity and to be increased gradually over 1 week to 10 days and only one food to be introduced at a time.
Hope I have answered your query.