You need to sign up for create your own device, node and field: https://iotguru.cloud/signup
The variables of the API call:
- {nodeKey} - the API key of your node
- {message} - the message (URL encoded)
Read the tutorial steps: https://iotguru.cloud/tutorials
Check the REST API: https://iotguru.cloud/apidocs/push
http://api.iotguru.cloud/push/freeText/{nodeKey}/{URL_encoded_message}
See the example HTTP call below (don't forget to replace values!).