Assalam O Alaikum Beeeneees and all others.
You are darn-right.
please tell me the meaning of darn-right ?

It’s just an emotional and/or emphatic version of “you’re right”.

Beeeneees please brief me about the usage of idiom “here you are”.

It’s a very informal expression which means ‘You are absolutely right.’

Thanks our tort system.
please brief me about the usage of idiom “here you are”?

Used idiomatically, this is said when you hand something over to someone or do a favour, usually to draw the recipient’s attention to the exchange. It is equivalent to “thank you” when receiving something.

Thanks Beeeneees.
My second question please?

Wow Beeeneees thanks.
Now its quite clear.

Now it is quite clear.
now it’s quite clear.

Either is fine because this is an informal situation.

If you were sititing an English exam then you would need to use the long version:
now it is quite clear.