Possibly look at something like jqModal
http://dev.iceburg.net/jquery/jqModal/[
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There are lots of different plugins for this type of thing, but the idea would be as follows
* User selects from the list
* Either 'on select' or after clicking some sort of action button e.g. 'comment on this employee', show the dialog
* The dialog can contain any html elements you like to capture the input from the user, e.g textarea for comment
* When user clicks OK on the dialog, perform database operation and update the employee information