This has been asked many, many, many times before so please search before you post:
https://devforum.roblox.com/search?q=learn%20code%20category%3A54
You should read through the topics that I have linked as they almost all give very similar answers like look on YouTube for tutorials, look through free model code and look on the developers hub.
I self taught my self to code by looking through free models and using the developers hub to look up API references and tutorials.