Fill in a Spreadsheet with Data -- 2

We are having a spreadsheet which represents events for each outlet in a span over a year. We want this spreadsheet to be in a way, that colleagues can choose a start and an end date from a drop down menu, plus a description of that event. Once those parameters are set, that particular event then needs to appear on that spreadsheet, preferably in a color code. So that in the end, everyone who makes an input of their respective event, will then create a generic events calendar.