If you are a beginner you better start with demo account. It will give you better insight of the real world trading with no risks. You’ll be able to learn better.
My opinion slightly differs in case of demo account.
As the question says "How do I start
investing in the stock market as a beginner?"
So investing is continues and time consuming process.
If you want to become rich overnight, adios amigo
First things first
Understand basic concept of market like what is Share, Stock, Nifty, Sensex, Trader, Broker, Brokerage etc
Coming to demo account, start trading with small amount/quantity like 500 to 1000 and get the zest of it.
Unless your real money is involved you will not be serious and will never feel the pain / joy.
Once you are done with above read some articles or take a course for technical analysis and try to analyse few stock and move ahead gradually.
All the best for your Journey ... !!!
Thanks,
Satyajeet