g_force:
... is it complex?
Yes
... because the contents of the centre column are, as I said, the most "dynamic" (ie: content comes from a large number of places, depending on what the viewer instructs the site to do:
Here's a list of SOME of the types of content that get chucked into the centre column
- view a product list (in a large variety of options)
- view a specific product's info
- view a defined page
- view an ezpage
- progress through the checkout procedure
- view personal "my account" data
- search results pages
- LOTS more...
Each of these "pages" is constructed by specific php files - in some cases, SEVERAL files (module, template, language...) contribute to the positioning and nature of the content.
... you will need to know HOW each page type is constructed, and then work out WHERE you can put the search box code.
(good luck!)