How to set up Filters

Your demo site shows a Filter by Tags, which I would like to implement, but I am not sure how.

The "image" content type that you have set up clearly has more fields that I get by simply installing image and image browser, but I can find no documentation on what I need to set up to emulate this. Is this a taxonomy field or what?

Also are there any additional configuration settings for image browser required to get the filter to appear?

And while I am at it, your demo shows a "Link To" field on the Insert page, which I don't get - is there some other configuration I need?

With thanks.
Tony