You will have to log in first.
You will be able to see it on the top right of your Google search page. The first time you click on it you will be asked to enter your country and time zone, then click save.
You will taken to a calendar that it on the day view. Change it to month!
To enter your new events double click on the empty square of that day. You can make the event for a whole day or a particular time span. Click save.
To embed your calendar click on the cogwheel to take you to the calendar settings.
Click on CALENDARS- then click on your calendar's name.
You will see the embed code that you can just embed it or you can customise the colour and size of your calendar before you embed it.
Read your options then copy the embed code at the top of the page.