How to start solids & water with baby

Hi mummies, when you start giving water and solids to your baby once they hit 6 months or so, how do you introduce it and how much to give? How much water to give at one time or in a day? Do i still give in his milk bottle? And how much of solid (eg porridge) to give at one meal? And how many times a day/at what time and how to interval with his milk feeding? for porridge can use any rice grain? Same as what we eat as adult? What kind of food can i start introduce aside from porridge. Thanks alot mummies! - First time mum