Creating JSON Extractor

I am send logs from Syslog-ng to Graylog. Following the instruction on this documentation on oneindentity website. However, I am stuck on creating of extractor.

I have found a link on graylog mentioning on How to use a JSON Extractor. I try following the video but seem like the the link has been updated. The current marketplace link is link to the Graylog community marketplace. So not sure if it the correct one.

What I have done is the following:

  1. Creating an raw TCP input on Graylog
  2. Configuration the setting on syslog-ng

Currently I am using Graylog version 5.2