tim1000
After everything is added to either your root or a folder (I don't know where you told composer to install it), then you go to the corresponding URL. For example, if you installed it in your main public_html directory, then you just go to yourwebsite.com and an install page should appear. You must fill out the information on that page. Or, let's say composer put everything in yourwebsite.com/flarum, then you would need to go to that URL to finish installing.
Before that though, did you create a database? Bluehost has cPanel. In cPanel go to the databases icon. Then create a database. Then create a user for the database. Then, add the user to the database with all privileges. I'm sure Bluehost has related tutorials if needed.
When you see the install page, it will ask you to input that database information you just created.
