Here is what I do know:
One: To link a static block to a .phtml page I add the following PHP in the proper location of the .phtml file:
<?php echo $this->getLayout()->createBlock('cms/block')
->setBlockId('my_custom_block')->toHtml() ?>
And create my static block in the Admin section.
Done.
Two: If I upgrade Magento, the form.phtml file I edited will be overridden since it is a core file.
Three: I need to create a duplicate form.phtml and place it in my somewhere in my theme. Let's call my theme "customtheme" for clarity.
Four: I need to go to admin > configuration > design and add customtheme as the default theme. Perhaps I have to add it in templates and/or layout as well.
My Question:
I have done all four things. I have created a directory app/design/frontend/default/customtheme/template/contacts/form.phtml and cleared the cache and I find no changes.
To make sure that my changes should be noticed, I edited the core form.phtml located in app/design/frontend/base/default/template/contacts/form.phtml and my changes were seen.
My Question: What directory should I be placing my custom form.phtml file in to ensure my changes do not get discarded on an upgrade and to ensure magento loads this file instead of the core form.phtml file?