You can get a command block in your Minecraft world using a special chat command. You'll need to have both Cheats and Creative Mode enabled in your Minecraft world to ...

In survival mode, this only works if you actually have the block you’re facing. Otherwise, nothing happens. And in creative mode, whether you have the block in your inventory or not, it will always ...

Enabling cheats in this version of Minecraft can be done at any time, and it is actually quite simple whether you are starting a new world or loading a game for a world that is already in progress.