To reboot your new guest use the command xm create GuestName where GuestName is the name you entered during the initial installation. Guest configuration files are located in /etc/xen/.

Once you have started your guest using the command above you can use virt-manager to open a graphical console window for your guest. Start virt-manager, select your guest from the list and click the Open tab, you will see a window similar to the one below: