Emergency!! Need help uploading XAMPP website to web server

So I made a website using XAMPP (PHP website that has login functionality and connects to a database on Amazon Web Services) and I am using MySQL as the database language. To connect to my website, I just go to: http://localhost/users/index.php

So now, after the website has been made, (login works, and gets the specific information from the AWS database corresponding to that user, and I've done all the testing already) I then uploaded all the files inside the users folder into a directory in the web server (using Netfirms as the host) but I get the following error:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Can anybody please help me with this? I need the website live by year end and I am freaking out!! Please and thank you all!