Demonstration
Step-by-step guide
Aim crosshair
Place your crosshair here

Throw
Press the keys to throw the grenade
Hint
From spawn position B, align your crosshair with the intersection of three brick seams, then pan right to the top-left corner of the rightmost brick, then hold Shift, tap W and jump-throw with left click.
Practice from exact position
Paste in CS2 developer console to teleport to the throw spot