To add a pageName parameter, follow these steps:

1. Navigate to the page in the Service. Note the URL in the browser's URL bar after the last/mark, as shown in the bold portion of code:

https://app.powerbi.com/groups/ce5f0fba-5cfe-4911-8c19-6cd0c4a05316/reports/a9b01471-0982-4e14-bbf7-ddb60a89ab43/ReportSectione40aa5b8b28a3bc92793

This is the report page name portion of the URL.

2. To force this particular page to be displayed when initially loading the report, edit the embed code as follows:

https://app.powerbi.com/reportEmbed?reportId=a9b01471-0982-4e14-bbf7-ddb60a89ab43&autoAuth=true&ctid=4a042743-373a-43d2-827b-003f4c7ba1e5&pageName=ReportSectione40aa5b8b28a3bc92793