When I type a simple text Document on Pages or Notes, is this content saved when I sync with Itunes?
Also, I need a very basic explanation of how to save a Pages document to Dropbox on my ipad. I think I am supposed to use an app like PlainText or Elements to do this, but I don't know how.
I am new to Apple products. If anyone can tell me how I can get a basic explanation, I would greatly appreciate it. Thank you.

iTunes performs a basic backup of app content each time it syncs. I don't recommend depending on this backup for important files. You can only restore by restoring the entire iPad, and iTunes only keeps the most recent backup, which is easily overwritten by mistake.

Here is a link to another thread about Numbers and DropBox. It applies to Pages as well.

Dropbox and Numbers