iphone how to set my language to English?

its in Chinese. my father bought last week from China. is what wrote on the back of the box. MB500ZP / A White iPhone 3G, 16GB Designed by Apple in California, Assembled in China Model A1241

http://support.apple.com/kb/HT2371 When I got my iPhone it was already in English, but Apple showed how to set too English. (:

iPhone 3G, 16GB