First you need to read the Influxdb docs so that you understand the concepts in influxdb. Make sure you read the right docs for the version you are using (1.8 or 2.0) as they are very different. I think most still use 1.8, waiting for 2.0 to fully stabilise.
Are you going direct to influx from telegraf or are you writing to the database from node-red? If using node-red then, once you know about Influxdb Measurements, Fields and Tags, then you can use node-red-contrib-influxdb to write (and read) to the database.
