I wanna start programing in lua but i dont know how to start
Learn programming in Lua. There are many websites online that can help you with that.
FiveM specific tutorial can be found here [How-To] Create a basic script
This helped me to get started
https://www.tutorialspoint.com/execute_lua_online.php
also i would really suggest not to begin with fivem script because it will comfuse you