Publishing your site is a simple process.

Just click on the green publish site button on the right of the Top Toolbar.

Next, choose one of the options: would you like a temp url for your site? Do you have an existing domain you wish to connect? Or maybe you want to buy a new domain?

Click on the option of your choice, and move on to the next step: 
selecting the type of license you want, and after you pay you are all set!