how to activate my iphone with itunes

Connect it to iTunes and follow the prompts.

******before starting anything go to Start->Control Panel->Administrative Tools->Services-> Find from the list "Apple Mobile Device"->Right Click->Stop->Right Click->Start******

this is the best way man. if it is a gsm phone(which means that you need a sim card), insert the sim card in the sim tray(which is on the top of the 3g and 3gs and on the left side of 4, 4s), turn on the phone without connecting it to itunes, select country, language, wi-fi network, and after that choose if you want to set it up as a new phone or restore from itunes/icloud. if you choose itunes only THEN connect it there.