Help with MQTT and Arduino

Switch MyItem1 { http=">[ON:POST:http://sample.com/myitem1:on] >[OFF:POST:http://sample.com/myitem1:off]" }

Assuming you don’t want the version coming with raspbian, you need to do some more commands (read the section at the bottom " Installing from the Mosquitto Debian repository"

That is something you won’t find in depth in this forum, but there are a lot of script examples in the net.