Hi there @Balveer_Gangwar!
Don here from Shopify.
Thanks for letting us know here about your interest in developing apps as a Shopify Partner.
The first thing I would recommend is to create a Shopify Partner account if you haven't already.
When you've got one set up, you can then proceed to check out our help docs on how to make Shopify apps.
Have you worked as a developer before elsewhere before considering Shopify?
In either case, I'd recommend you check out our Partner Academy as it can help you to develop your skills in a beneficial way.
Take a look at the resources shared here and let me know if there's anything else we can help out with!