How to Embed a Google Calendar into a Web page (Ning, Blogger, etc.)
(scroll below for visual step-by-step)
1) Click on Settings in My calendars.
2) Click on Shared: Edit settings under the calendar you desire to embed.
3) Click on Calendar Details.
4) Copy the code in the Embed This Calendar section, starting with <iframe src=.... . You can customize the look of the calendar in the Ning site by clicking on Customize the color, size and other options right above the box with code. Simply copy the code when you have the look you want, and paste it in a Ning text box.
5) Add the code you copied in a text box and voila...you have an embedded calendar =)

Also, check out the video tutorials to demo the process:
http://www.screencast-o-matic.com/watch/cjX0cTnTn
http://www.youtube.com/watch?v=2tnYwbs-yDk&NR=1&feature=fvwp

1) Click on Settings in My calendars.


2) Click on Shared: Edit settings under the calendar you desire to embed.