Setting up the Console
If you already know how to open your console, skip this part.
If you don't, then in CS:GO, go the settings cog on the side of the screen.
In the settings menu, click the "Game Settings" tab and change "Enable Developer Console" (~) to "Yes".
When in game, press the tilda key to bring up the console.
This key should be located next to the 1 key, and above the "TAB" key.