Well, in a nutshell, you create a TV, give it an input type (what will be seen when editing a document) and a default value. Check the box for the template you want it to be used with. Now, every document using that template will have another field (what you assigned it as the input type, for example you’ll get another Rich Text field if you specified that input type). So you can edit this for every document, and you can put the TV tag ( [*tvName*] ) wherever you like, in your template or in your document content.
I tend to put a TV in my sidebar:
<div id="leftSidebar">[*leftSide*]</div>
I use a "binding", @INHERIT, for my default content, and make the input type a textarea. Now, I can edit that for my subheading container documents, and all of their children will inherit that value, so I can have a different sidebar for each section of my site. In the textarea field for each parent document, I can put HTML code and chunks and snippet calls, so my sidebar can be completely customized with menus or whatever I want for each section.
The best way to get to understand the full power and flexibility of TVs is to play around with making up a few and using them. Just make sure that you check the box for the template you want to use them with.
Of course, TVs are a lot more flexible than that. For example, you can give it in input type of "image", and each document using the assigned template will have an image input field. If you also specify an output "widget" of image, you’ll get the proper image tags output to your page.
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