If you used Method 1, you should browse to the FireBrick's web interface as follows, or you can use the IP addresses detailed:-
If you used Method 2, you should browse to the FireBrick's IP address as listed below:-
If you used Method 3, you will need to be able to access a list of allocations made by the DHCP server in order to identify which IP address has been allocated to the FB6000, and then browse this address from your computer. If your DHCP server shows the client name that was supplied in the DHCP request, then you will see FB6000 in the client name field (assuming a factory reset configuration) - if you only have one FB6000 in factory reset state on your network, then it will be immediately obvious via this client name. Otherwise, you will need to locate the allocation by cross-referring with the MAC address range used by the FB6000 you are interested in - if necessary, refer to Appendix B to see how to determine which MAC address you are looking for in the list of allocations.
Once you are connected to the FB6000, you should see a page with "Configuration needed" prominently displayed, as shown below :-
Click on the "edit the configuration" link (red text) to perform the initial configuration.
You will then find yourself in the normal configuration editor where you can make changes to the default configuration to suit your needs.
You will need to create at least one user as once saved you are prompted to login using the username/password details you provided.