DannyHamilton, Thank you

I am very grateful for your assistance.
If you are using Bitcoin Core, then you can use "listunspent" to get the list of all unspent outputs that the wallet has full control over. You could also use "getrawtransaction" and/or "decoderawtransaction" to get information about specific transactions if you know the transactionID.
Now (7.30 AM France), my Bitcoin Core deamon is downloading the blockchain ( 345379 of 388985 blocks downloaded...),
transaction is
"block_height":387184
so I have to wait that it download that block to test it

I will have to study now,
- how to determine size of transaction before create it (to determine the appropriate fees)
- create it with
CreateRawTransaction - sign it with
SignRawTransaction- send it with
SendRawTransactionThank you for you help
