Without knowing exactly what the log looks like it's impossible to give specific help, but I can offer some general advice:
- Read and make sure you understand the examples in the documentation: https://www.elastic.co/guide/en/logstash/current/config-examples.html
- Write a grok filter to extract fields from the event text. If you're not very familiar with regular expressions http://grokconstructor.appspot.com/ can be of great help.
- Use a date filter to parse the extracted timestamp into the
@timestampfield.