Automate website stuff

I want to automate some website stuff in chrome browser, I want you to click on the few button for visiting next page or to redirect to next task, and at a specific page I want to paste some data like credentials and again click on few button and lastly I want to copy a OTP from gmail id and paste it in the last page of my website and click it on the submit button.
It should be done using .Net or Javascript (Like google extension).
There is also one numeric captcha which can be autofill using OCR