How to Embed a Google Calendar
First, create the google calendar.
create a calendar

Make sure you make the calendar public.
make calendar public

Answer Yes to this prompt
yes to make calendar public

Once the calendar has been created, go to the calendar settings.
go to calendar settings

Customize your calendar by clicking the "Customize the color, size, and other options" link.
customize the calendar

Make the calendar look how you'd like. You can't do too much to the colors. But you can change the size. The width is something that you'll want to play with to make sure that it fits on your page.

Then, once you have it as you want it to look, copy the html code above the calendar into your webpage. If it's too wide, adjust the width on this page and then recopy the html code to your website.
copy html

Here is how the above calendar looks, embedded into this page.

Updated: January 2015