How do I show an embedded excel file in a WebPage?

This has to do with the local person's browser set up and not really anything you can do on your end. If they click a link with the .xls(x) extension, the browser determines if it wants to open it itself or in a new window.

Here 2 microsoft pages on how to change these settings:

http://support.microsoft.com/.../how-to-configure-internet-explorer-to-open-office-documents-in-the-app

http://support.microsoft.com/.../embed-your-excel-workbook-on-your-web-page-or-blog-from-sharepoint-or-onedrive-for-business

You should try using the Excel Web App Embed feature that lets you embed tables and charts from Excel directly on your Web Page. You can even let users interact with the spreadsheet so that they can sort and filter data and use your spreadsheets formulas to calculate make their own calculations all without altering the source.

The Excel Web App and storage is all free from Microsoft. Any data you embed on your Web page can be viewed by all the major destkop and mobile browsers and when you update your spreadsheet the data on your web pages is automatically updated as well.

I think your best bet is going to be extracting the data out of the Excel file and displaying it in a regular HTML table. Excel isn't exactly safe to invoke from a web page and not everyone has it anyway.