extjs 2.2 project/php/mysql

I need urgent help with a small extjs project. Basically I have generated a calendar in php. On each day I have 3 possible shift allocations. I'd like to create an html link that opens an extjs popup window that allows assigning of shifts. The following variables would be passed to the window: date, shift, itemid. The window would check a mysql database for available people for the shift on the given date, for the given item and return a select box. I'd also like to populate the window with a bit of information from the database regarding what's happening on that day. For now you can ignore the database links and just hardcode in php the text/combo box. When the form is saved the database would be modified and the page that the link originated from refreshed.