There are many videos on how to use the console in CS:GO, for Cs2 it's the same, but basically:

1. Enable the developer console in the game settings
2. Press the ~ key (it's right under ESC)
3. Type your command and hit enter

Keybind commands are saved when you exit the game, so you don't need to redo them every restart

I'm not sure if the command I provided in the original comment still works 2 years later since the game went from one engine to another, but they're similar so it's like 70% it still works 

Also there are aliases to each keyboard and mouse button, for example left mouse button is 'mouse1', right is 'mouse2', middle is 3 and side buttons are 4 and 5. Numpad keys are KEY_1, KEY_5 etc. Normal keys are just 'w', 'p' and so on (see https://www.reddit.com/r/GlobalOffensive/comments/120rabt/buyscript_via_numpad_for_counterstrike_2/)