1). Go to your Event Types at https://freebusy.io/app/share
2). Click Configure on the event type for which you want to take meetings on your website
3). Expand the first configuration section named after your event type
4). Click Embed Code button
5). Copy and embed code to paste in your website editor.
Go to your website editor view. If your website allows embedding via IFRAME, paste the embed FreeBusy HTML code when prompted. Now follow your website instructions for how to embed code from other applications.