Install files means FTP to your server.
Your File Transfer Protocol log in details will have been supplied to you when ordered your hosting package. ie Hostgator etc
Then you will need to use a FTP program, I use Filezilla but you can use any you wish or are more comfortable with.
Once loaded you transfer files from your PC to your sever following exactly the same path.
We use a method called 'Drag and Drop' ie Highlight the files you want moving and drop them into your public_html folder, all corresponding files and folders will land in the correct places.
Now its time to install the .XML