You have survival and creative mode. In creative mode you have all the blocks you want to make great buildings, dont need to mine them and you can even fly arou

You have survival and creative mode. In creative mode you have all the blocks you want to make great buildings, dont need to mine them and you can even fly around. Start with your son in creative mode and practice building basic stuff. Then learn how to go survival mode watching some youtube tutorials. Small kids really enjoy creating their own houses, towns and megacaves in creative, when they feel comfortable they ask to go to survival on their own. Then they discover roblox (that has hundreds of mods) and there is no back! Hope it helps.