Buenos and Buenas and Masculine versus Feminine ?'s

Question

I am confused as to why Buenos and Buenas, what is the difference between saying these when saying good morning and good night?

Also, I understand the feminine versus masculine, but what If I am talking about someone or to someone? I know I would say about myself " Estoy cansada" but what if I am saying "He is tired" or you look tired ( to a man ) Would I then say, "El es Cansado" or "Te ves Cansado"?

Just need a little clarification, estoy Confundida.
Gracias Kim

Answer 1

'Días' is masculine plural, hence the adjective 'buenos.'
'Noches' is feminine plural, hence the adjective 'buenas.'
If he's tired, you would say 'él está cansado.'
If she's tired, you would say 'ella está cansada.'
If you (masculine) look tired, you would say 'te ves cansado.'
If you (feminine) look tired, you would say 'te ves cansada.'

Answer 2

I understand now.

Gracias, Kim

Answer 3

That last one looks a little specious to me. Normally one would say Can ver be used in that context? I thought ver was more like mirar or to look at.