How do I mail from the US to Ecuador?

Can I use USPS or do I need to use UPS or Fedex or something? Does Ecuador use postal codes? And also what do u think it will cost to mail some photos? Thank you!

But I mean does the USPS send mail outside of the US??

Also I read on wiki that Ecuador doesnt use postal codes & the addresses I have- dont have postal codes. But I saw another website saying they use 6 digit codes.. ???

Air Mail (as in letters in envelopes, postcards and such) from the US normally take between 7-10 days. Air Mail costs about 30 cents, but it all depends on the weight.

Ecuador uses six-character postal codes. The first character is the province letter (ISO code of the province). The next two characters are digits indicating the canton. The next two are digits indicating the parish. Finally, one additional letter identifies a local delivery area.

You can find the postal codes at the page below.
http://www.statoids.com/uec.html

USPS does deliver internationally. For a 1 pound "Priority Mail庐 Flat Rate Envelope" to Ecuador the cost is $11.00 (with an estimated delivery time of 6 - 10 Days).

You can use the Postage Calculator on the USPS website to calcute Domestic and International shipping rates and estimated times.
http://ircalc.usps.gov/

Probably a couple of dollars for the postage. If it's a letter, then, yes, the post office. If it's a package, UPS might be cheaper. I would go to the UPS store, as they service both, and can probably do the comparison right there. They also probably have the correct postal codes, I think they do use them, I think every country has them, except, maybe the Vatican.