Promising is not an idiom -- it is a word. Idioms are phrases.
"You" is not an idiom. It is a pronoun.
to support
This expression means real and simple.
pleasant and easy....
It means to get married.
It means that is the essence of it. Similar to the expression 'in a nutshell'.
a mass where prayers are sung
i believe it means: to hope that...
Go nuts; crazy.
timid,coward
That expression means that he is conceited, egotistical, pompous or vain.
stop doing what you're doing