How to create extension

Please i try to create an extension and this is the feedback am getting in my freepbx

Name/username Host Dyn Forcerport Comedia ACL Port Status Description
300 (Unspecified) D No No A 0 UNKNOWN
1 sip peers [Monitored: 0 online, 1 offline Unmonitored: 0 online, 0 offline]

The output you quote relates to devices not extensions. FreePBX does not use Asterisk terminology and, if you want to use the GUI,you need to use FreePBX support resources, such as