Está un poco preocupado/a por nosotros.
It's cuba.
They were worried that the Americans would soon try to have the Spanish territory secede from the remainder of the colony and join with America. This fear was entirely rational considering that Texas (part of Spanish Mexico) actually did exactly that in the 1830s.
Cuba is the Caribbean island that worried the US, because it was only 90 miles off the US coast.
United States in Spanish is Estados Unidos.
you say: "no nos olvides"
Aqui hay un poco acerca de nosotros or aqui hay algo acerca de nosotros
Los Estados Unidos
Dólar americano.
If you wan to say 'join us' in Spanish language, you will need to use the words: 'Unete a nosotros', this is if you want to say it in imperative form.
Los profesores nos ensenan (en espanol) = The teachers teach us (in Spanish)
los estados unidos
de los Estados Unidos