Hi,

Are you referring to the Alt text tag that appears when you hover over an image, or a Kontera type box that pops up with more information when you click on a word and/or image? There are several solutions available, need a bit more detail as to what you are trying to accomplish.

can link yet but google for "javascript tooltip" and you will find

It is as simple as an ALT tag. I mean you can use more complex tools with more details and features but basic is sometimes the best.