I want to implement the 20 30 40 numbering system for calling my defense.. Can someone please give me some advice on how to implement this? I understand the premise, but I am not sure how to call my 2-2-1 or diamond full court presses out of this numbering system or how would I call my 1-3-1 defense using this system. What would be the difference when I call a 3-2 defense versus a 2-3 half court defense? Any help would be appreciated.

Nornally the first number is the type of defense. So examples could be...

1 - man to man
2 - 1-3-1 zone
3 - 2-3 zone
4 - 2-2-1 zone

The second number is how far it extends...
1- quarter court
2 - half court
3 - 3/4 court
4 - full court

So 11 would be quarter court man to man. 14 would be full court man to man. 22 would be half court 1-3-1. Etc.

Here's an article with more info:
https://www.breakthroughbasketball.com/defense/multiple-defense-system.html

Also, I see you posted in youth basketball area. I definitely would keep is simple with youth and teach them fundamentals. I strongly recommend staying away from multiple defenses (one or two) so they learn good habits.
https://www.breakthroughbasketball.com/defense/age.html

You win a lot of games by switching defenses but I find young teams rely on it too much and then don't develop fundamentals. Switching defenses works really well at youth levels and then once they hit varsity it doesn't work nearly as good because their minds are developed to handle the switching. I see too many coaches use this technique as a crutch and then they don't learn how to defend well in the half court or even realize their true weaknesses that they should be working on (it hides shortcomings). Personally I don't think you should use switching / multiple defenses until varsity level in high school.

I apologize, I posted this in the "Youth" area by mistake... I really do need advice on this! I appreciate your reply, thats exactly the help I needed

I kept it pretty simple on my 7th/8th grade defensive sets. Our base defense was a M2M and we had one zone defense (rarely used it). I found I needed a few offensive numbers for the other's teams 2-3 or 3-2 zone defenses though. I had 2 presses and we practiced them a lot. We just didn't have enough time to really practice a bunch of sets and be effective. I more in the camp of having a few different looks on offense and defense, but doing them really well. I think you can usually tell if your press is working early on against a team.

The other teams seemed to catch on to our numbering scheme so I used to have numbers that meant nothing and my kids knew it. The numbers might sound similar to our actual live press, so I'd shout out a few before we took a free throw. Don't know, it must have been the Peyton Manning in me.