You need to modify the router's configuration using the JUNOS CLI.
You need to be in configuration mode to configure the router:
aviva@router1> configure Entering configuration mode  aviva@router1#
When you want to modify the router's configuration, log in to the router, enter configuration mode as shown in this example, and then create a hierarchy of configuration statements that define the desired router operation. There are other ways to configure the router, which are discussed later in the chapter, including loading a configuration file from a remote server or from the local router and loading a previous router configuration.
When you want the configuration to take effect, you must activate, or commit, it.
Router Configuration and File Management
Basic Router Security and Access Control
Routing Policy and Firewall Filters