Making an application live majorly depends on the type of hosting you are having along with the method to access you are provided for that hosting.
I am assuming that you have shared hosting with Cpanel.
Please go through the below steps to make your PHP application live.
Your code files are live now.
If your application is static then the above steps should be enough for making it live but if you have a database in action then you also have to create and connect a database too, to the application.
Below are the steps to create a DB in cPanel
Connect your Database to your application through config or how so ever you have designed to it.
For any concerns and doubts feel free to ask in comment section.