Hello @db77,
You wrote
I am here

First, if my problem need a new thread, I can open a new thread to not disturb you... and delete my post in this thread. Say me...
No, this thread is totally fine, as your topic fits exactly in this discussion. No, you do not disturb me and there is no need to start a new thread.
Yesterday, I install these components :
mosquitto-2.0.12-install-windows-x64.exe
node-v16.13.0-x64.msi
MQTT-Explorer-Setup-0.4.0-beta1.exe
But I read yesterday in your post that I don't need this

I
That is fine, but I did not say, that you do not need this.
I said:
For what you need, Domoticz is not required.
and also:
Required:
1. Hardware, such as a Raspberry Pi.
2. Mosquitto, installed on that hardware.
3. Node Red installed on that hardware.
4. risco-mqtt-bridge on that device (See:
https://github.com/lucacalcaterra/risco-mqtt-bridge)
5. Android device
6. Time to design your system, time to program/configure and time to test.
As far as I can see, you did not install yet Node-RED and the Risco MQTT bridge.
I will try to answer the questions below.
With your MQTT I don't know what to do ...
1 - Do I have to create a port forwarding that goes on my Risco system?
2 - Do I have to create an account on a server and which one?
3 - When I launch MQT explorer, what settings should I use?
1. If you want to receive
MQTT messages from outside your LAN, you will have to forward a port to your local device, that runs Mosquitto.
By default it is port 1883. But for the moment you do not need that, as the Risco MQTT bridge is intended to run also on your LAN.
2. You do need an account for the Risco Cloud service, but see my comment later on in this post.
3. For the setting of MQTT Explorer.
Step 1: Open the MQTT Explorer.

- Screenshot_MQTT-Explorer1.png (12.41 KiB) Viewed 1428 times
Step 2: Click + "Connections"
Step 3: Fill out the fields as shown below:
Name: whatever you like
Validate certificate: Off
Encryption: Off
Protocol: mqtt://
Host: The IP Address of your Mosquitto device
Port: 1883

- Screenshot_MQTT-Explorer2.png (44.42 KiB) Viewed 1428 times
Press "Connect".
Remark,
This morning I have been reading a number of messages about the now paid service of the Risco cloud.
You can do the same and should read:
https://community.home-assistant.io/t/r ... nent/82359 and also
https://community.home-assistant.io/t/r ... tem/228907
I also saw at the issues at:
https://github.com/mancioshell/risco-mq ... -assistant and
https://github.com/lucacalcaterra/risco-mqtt-bridge
They both use the cloud API of RISCO, which has become a paid service. I don't think it is a good idea to install Node-RED and one of these python scripts at the moment, as also these script rely on the (now paid) cloud service.
We have to wait until someone develops a direct connection to the API, but that will be difficult as I also read that it is is encrypted.
You can try to install one of the python scripts and see If you get an answer in MQTT Explorer. As long as it woks, it works.
Regards