But How do I get this 'Command Block?'

To Get a command block:
/give 'Player/@p/@a/@r' 'Item' 'Amount' 'Data' 'Datatag'
Complicated? Well not if you want a Command Block:
/give 'Player/@p/@a/@r' '137/minecraft:command_block'
Item is Command block and amount if you leave blank gives you 1
Amount: How much of that Item
Data: Like Wool has different Data's
35 is Wool
35:1 is Orange Wool the 1 goes into Data!
the Datatag you Don't Worry about it you don't need it for a Command Block...
Now there is your Commander Room! Full of Command Blocks!
Notice: Command Blocks are not found in the Creative Inventory.