This is actually, I want to share, how I learned the shell scripting. It may be helpful for beginners. I am writing it step by step so that it will easy to understand:
STEP 1: Do your task manually & prepare the steps.
If you know the basic Linux commands, it will help you to write a shell script. I am not writing the basic Linux commands here, you can see check here http://www.comptechdoc.org/os/linux/usersguide/linux_ugbasics.html