Launch Aspire (if it's not already running). See:
Add a Publish to Kafka drag from the Publish to Kafka rule from the Workflow Library, and drop it to the Workflow Tree where you want to add it. This will automatically open the Publish to Kafka window for the configuration of the publisher.
In the Publish to Kafka window, specify the connection information to publish to the topic.
Once you've clicked on the Add button, it will take a moment for Aspire to download all the necessary components (the Jar files) from the Maven repository and load them into Aspire. Once that's done, the publisher will appear in the Workflow Tree.
For details on using the Workflow section, please refer to the Workflow introduction.