Well, typically it's all said in the tutorial I linked to.
From what you're saying, it seems you want to show INR only by default. Means you'll need to set only INR to both "published" and "displayed".
You can set more currencies to "displayed" - these will then show with the help of the currency switcher module.
You can also set more currencies to "published" - customers should then be able to pay in these currencies as well.
The rest then depends on what currency you use for product pricing, payment methods, etc.
If trouble persists despite tutorial, other documentation and else, best post a link to your site and screenshots of relevant configurations.