What did I tell you , I said search. You are so lucky I'm being nice right now and I'll give you the links to start you off. :
Guides :
1.
AMX Mod X Scripting Tutorial - This tutorial is the official AMX Mod X Scripting Tutorial , it isn't finished yet so don't get angry but it is very useful.
2.
Scarzzurs Scripting Tutorial - This should teach you important stuff that is inside of a plugin and structure.
3.
Small Language Document - This is will teach you small , the language AMX Mod X plugins are written in.
4.
Google Scripting Tutorial - Always useful to use google search.
Other things you can do to learn how to script :
1. Read others plugins and see how they made it , if you are stuck ask that author questions.
2. Read the AMX Mod X natives in the Include folder , those are what you use in plugins.
3. Ask questions on the Scripting forum , that is how you learn.