Create an index.
Create Index-Time Field Extractions and deploy to Indexers
Send events to index on Indexers
Create Search-Time Field Extractions and deploy to Search Heads.
MOST Search-Time Field Extractions can be created through the GUI on the Search Head (examples of exceptions include KV_MODE). If you are configured correctly, NO Index-Time Field Extractions can be configured through the GUI of Indexers.