I am working as an assistant sales manager in a truck sales.My management is saying send a mail to a indian company asking about their dealership in Kuwait .how can I write ?

I really don't understand what you're asking? Are you having problems finding the address of the company? Do you not know what to write, what to ask?

If you want to know the details you should write in the letter then it's best to ask your boss exactly what he wants to know so you can express that in the letter.

You really have to talk to your boss about this and I would suggest showing him the letter before you send it.