DEMO using the server test.mosquitto.org

You can use any MQTT client with the following settings
Server : test.mosquitto.org
no login / no password
port: 1883 or 8081 for websocket
Topic: /AnnexTest

Or you can use the free MQTT online client

https://www.cicciocb.com/MQTT/

this is already configured so just 
- click on Connect
- write your message in "Publish Message" 
- Press "Publish" to send your message that will be shown in the scrolling display



A complete help of Annex32 can be found here
https://cicciocb.com/annex32help/V1.442/