Hi Donna,
There is no effective way to block access to the source code of any page: for the page to be readable by browsers and search engines, the source code has to be accessible, and so can be copied. That's just how the web works: HTML is sent as a text document and interpreted client-side.
There are a lot of people out there who disable the right click function to prevent others from clicking "view source", a lot of web designers can get around this very easily. I use an extension with my browser which allows me to view the source code without actually right clicking the interface of the website.
The only real way the source code can be hidden is if you convert your HTML into a flash which would take too long and become a hassle to maintain.
Here's a read which you may find interesting:
http://www.sitepoint.com/forums/showthread.php?t=419751