I need to change the name of the website: "Homepage Website localhost"; I don't know how. I have google cloud with bitnami as well. And the IP number point to my domain. Could you help me? Thank you very much.

You should set up a proxy server (Nginx or Apache for example) for reverse proxying.

See

https://www.odoo.com/documentation/8.0/setup/deploy.html

http://www.nkr1ptd.com/2014/11/using-nginx-with-odoo-version-8-on.html

http://www.nkr1ptd.com/2014/11/using-apache-with-odoo-8-and-ubuntu-1404.html

for help. Of course you need the corresponding DNS entry to point to the proper server address.

However, there is plenty of help around, Google is your friend.