To activate cheats, type in the console sv_cheats 1
Then type restart. After restarting you would be able to use the cheat codes.
You must know how to bind or put the codes in an equivalent key to fully use the cheat.
Example
To activate codes like impulse 101 equivalent to "$16,000", bind them to keys. Type bind mouse1 "+attack;impulse 101" at the console window to bind the "$16,000" code to the "left mouse" key.
Whats a console? The one that is usually or default is " ` " or " ~ " button in your keyboard. When you press this key there's a drop down windows which you can see more letters in it and you can type in it.
To see some splattered bones and body tissue
Bind mouse1 "+attack;impulse 102" then when you fire you will see bones, tissue, and blood will scatter all over the place.
Code = Equivalent impulse101 = $16,000 give spaceweapon_awp = Arctic sniper rifle sv_aim = Auto-aim with sniper rifle sv_gravity [-999 - 999999] = Adjust gravity gl_zmax[0-9999] = See and fire through walls and objects, default is 3600 lambert -1.0001 = See things brightly without flashlight cl_hidefrags 0 = View other players' frags cl_forwardspeed 999 = Faster forward motion cl_backspeed 999 = Faster backwards motion cl_sidespeed 999 = Faster side motion
+reload = Auto-reload enabled
-reload = Auto-reload disabled mp_c4timer [1-100] = SetC4 timer sv_clienttrace 9999 = Hyper auto-aim enabled sv_clienttrace 0000 = Hyper auto-aim disabled adjust crosshair = Change crosshair color timeleft = Reveal how much time is left on the map crosshair [1-5] = Disable the crosshair to enlarge when shooting mp_freezetime [seconds] = Set freeze period at the start of rounds. Set to 0 to disable, default is 6 [Note] mp_roundtime [3-15] = Set maximum length in minutes a round can last, default is 5 [Note]