Currency exchange procedure

What is the process of exchanging currency at the Post office? For example I will be going to U.S.A. and I don't speak Japanese.
How can I be better prepare when going to exchange currency at the Post Office?
Thank you

Hi
Are you going to Japan from USA or Japanese and going to
USA?.
In japan there are signs above counters saying in English what they do. Some
require you to take a ticket with number before going to counter due to people waiting. Most staff understand enough English to help. I used both US travellers cheques and cash
and had no problems. You will be asked where you are staying etc so have address
written down ready. Also passport will be checked and you have to countersign your name. Go and enjoy
Kiwi

i am in Japan and going to the USA.

Alternate means is just doing the exchange at the Airport exchange office or bank. Its a lot easier as they're used to doing currency exchanges.

I doubt all post offices even have American Dollars in hand. Especially if you show up to your local post office.

They can however do USD-JPY but harder the other way around.

Currency change booth or bank in the airport that is.

Can ATM machine be found in the Airport or in the city?

You can find international ATMs at the airport or in the city.

The following places:
http://www.japan-guide.com/e/e2208.html

ATMs only give out Japanese Yen.

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Back to what I was saying before you might have a hard time at the post office actually changing from JPY-into Foreign currency because the Post Office usually won't have foreign currency in hand to exchange into.

Its easier from Foreign Currency-into JPY.

For the original poster, be warned that US post offices do not exchange currency. Not sure if you meant post offices in US or Japan, so just a heads-up.

I think the OP was most likely speaking of Japanese Post offices (eg they "don't speak Japanese")