How to Send Excel Data over POST method

Can someone share the example code to send the excel data over POST method ?

filedata = event.file.getBytes()
system.net.httpPost(url,'multipart/form-data', filedata)

See this post. I expect the example could be modified for an Excel file, specifically I expect you would need to change the Content-type value to indicate the appropriate media type like 'vnd.ms-excel'. Let me know if it helps.