Thanks for your query.
Complementary feeding ,that is introducing foods in addition to breast milk should be started after 6 months.
You should start with liquids like boiled pulsed ware,boiled rice water initially and then introduce semi solids and later on solids.
It has to be a slow process and introducing one thing at a time.for 4 to 5 days and then add other.
like lactobaccilus sachet for 2 to 3 days.
Wishing your baby good health.