from where i can get free or purchase/exchange used stamps of any country?

Answer 1

Join a stamp club. You can get a list by location at http://www.stamps.org

Another good group to join is the International Society of Worldwide Stamp Collectors - lots of people to trade with in that group: http://www.iswsc.org

Sometimes you can find collections on eBay for not too much.

If you are under 18, join the Young Stamp Collectors of America: http://www.stamps.org/ysca/intro.htm

Stamp collecting is a GREAT hobby - have fun!