I would like to add Track clicks from google Adwords tools to my site. According google documentation I need to add to add calling gtag_report_conversion() to “book now” button. Can you, please tell me which file should I update.
Actually you cannot modify any file as during update all the changes you have made will be lost. However, you can add the required code with the help of child theme or you can use Simple Custom CSS and JS plugin(https://wordpress.org/plugins/custom-css-js/) to add the required code.
For detail assistance regarding how to create child theme, you can refer below given link: