Spot price is automatically derived from live market.
Enter the strike price and IV value.
For NSE stocks, use 6% as risk free rate if not sure.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.