Weaning food can be started from 5-6 months of age and in that initially in the initial  stage you can introduce some semi solid food to the baby like Banana mango plum boiled Apple  and then gradually you can start with some purie of carrot potato and some  other foods which can be given are porridge of suji  sabudana which can be prepared  in breast milk or formula milk. initially you can start with one or two  tsp which can be gradually increased up till at least three meals in a day

Yes can be given Paste or puree like. Most important to introduce food in a step wise manner, not all the items in the same week. One food for 1 week.