A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
You can use Excel Services JavaScript API to achieve this.
http://msdn.microsoft.com/en-us/library/hh315812(v=office.14).aspx
Above link show you how to create a basic JavaScript snippet to render a workbook using JavaScript API.
Below links shows you how to activate a sheet.
http://msdn.microsoft.com/en-us/library/ee660110(v=office.14).aspx
Do you need to save the changes made by user? JavaScript API does allows you to open workbook in View mode and not edit mode.