Hopefully, you now have everything planned out and ready to deploy. The general order of things is that you first configure your first URA server separately and independently. Then, you install the URA role on other servers that you want to use as entry points in other sites. Once they are ready, you enable the Multisite option on the first server and define some general settings such as entry-point selection options and support for Windows 7 clients. After this step is complete, you add the other URA servers as entry points. At that point, you can also enable Global Load Balancing, if you have the appropriate hardware and want to use it for this purpose.
Assuming you have your URA servers installed in all sites, with each having an IP-HTTPS certificate of its own, and an NLS certificate as well, you should be ready to begin. To be clear—you don't need to configure URA on the other servers—just install the role on them, and the rest will be done later.
To...