There are programs for scripting in AMX Mod X.
1. Custom ones like Small ED ( You can find on this forum )
2. Notepad
I'd use Notepad if I were you , it's really good , plus it's already on your computer. And trust me , nobody can explain how to script in AMX Mod X in one post , but I will give you some tips.
The best ways to learn :
1. Read as many tutorials you can find on this forum ( search for them and read the one in the AMX Mod X manual
www.amxmodx.org/doc )
2. Read other peoples plugins in the Plugins section , look at the code and see how they do certain things , take each function at a time , because each function does something according to how it's registered in the Public Plugin_Init() )
3. Ask specific questions in the Scripting Help section of the forum about how to do something or if you want to know what does what )
4. Read the Natives / Functions in the include files in your Include folder in the Amxx / Amxmodx folder or you can go to
www.amxmodx/funcwiki.php
5. Always know that nobody is going to baby sit you and hold your hand and talk to you on AIM or something constantly helping you , you will have to learn yourself , and don't give up just because it seems hard at first )