How do I get .aspx files to run on my ipad2

aspx files are ASP.NET web pages. You just type the url of the file into your browser's address bar. For example http://theSiteAddress/index.aspx.

If you mean you want to serve ASP.NET web pages you must be running Microsoft's IIS web server or a server with Microsoft extensions, which you can not do with an iPad. If you mean you want to open an aspx file for editing, these are just text files so use your favorite text editor and open the file for editing.