first, put your cursor over the command block then press E, then type the command you want. For example "/skin" then just like basic redstone, you can use the lever, pressure stone, target,... to activate that command block, then it will work (on this example u will change your skin).
The command block was so great, it's useful for making some interesting maps. But if we put "/tp x y" into that block it will work well until you save the code and then paste it again. It'll teleport you to "/tp , ", then u fall into bedrock!
