For enabling the console you have to change the shortcut of Portal 2:

1) Create new shortcut (left click at desktop and select new shortcut).

2) Input this path as location "C:Program Files (x86)ValvePortal 2portal2.exe" -console (this path is default)

3) Write a name of shortcut .

4) Run shortcut. After this game should be run. Now console will work.

5) To exit/open the console, just use the ~ symbol in game to use these codes in game.

Note: to make some of these codes work, you need to enter this code into the console: sv_cheats 1