In WordPress, clicking the Widgets submenu in the left Dashboard’s Appearance menu, gives you the option to add or remove sidebar items, or Widgets, already covered in this training here: http://project.norfolkparishes.org.uk/training/widgets/.
From the selection of Widgets on the left, drag Google Calendar into one of the Widget areas to the right. Give the calendar a name that will appear on your website and choose how many results to display.
The final thing to do is to insert the calendar URL which you must get from from the calendar settings back on Google. Towards the bottom of the page click on the XML button to bring up the calendar URL which you need to copy, and paste into Calendar URL 1 section in WordPress.
At the end of the URL you will notice the word basic, this needs to be changed to full for the calendar to display properly.
Click save to finish the process.