You could try looking into Hammer Editor for CS 1.6 map editing. There are some tutorials online that show how to change textures and add detail to existing maps
Why are you so worried about it? You still have time until at least Tuesday evening, and the quality of the drop doesn't depend on which day you pick it up. As an option, you can learn how to fix high ping in CS2 in an article by VRedux, which, by the way, has a lot of information about the bufferbloat that is currently happening in your game. You will also find a detailed description of how to solve this problem in several ways. Let me know if you managed to do it.
You could try looking into Hammer Editor for CS 1.6 map editing. There are some tutorials online that show how to change textures and add detail to existing maps