Hi,

I'm a french national and living in france but I want to migrate to usa and want to understand how can I live permanantly in usa with usa citizenship whether I can change my present nationality with usa citizenship or I can live in usa withmy own one.
Thanks

When you get married to a US citizen you become a "resident alien"
Meaning you get a social security card, alien reistration card (green card)
These two things allow you to legally work travel pay taxes get a drivers
License etc while keeping your xyz e;g french citizenship and after 5 years
If you feel like becoming a US citizen you can I don't know if US/france
Allow their citizens to keep dual citizenship other countries do allow it
You can call your local US consulate info line they can clear this for you
Hope this helps