can not change password ,because activationsession exprired

Thanks for the update, quan74.

More information on Activation Lock for iPhone, iPad, and iPod touch can be found here. It sounds like your brother may not have turned Activation Lock off prior to giving you the iPhone. Have your brother look over the "Remove Activation Lock on the web if a device is offline" section of How to remove Activation Lock for ways that he may be able to remotely remove that feature. If you need more assistance after this, look over the "Start a support request" section of the same page.

Be well.

Hey there, quan74.

Welcome to the Apple Support Communities! Thanks for posting about not being able to activate your new iPhone. We'd be glad to see how we can help.

A great place to start If you can't activate your iPhone would be to check out his page, as it details most of the reasons and steps to take. If that doesn't help, you may need to verify that your account is set up properly with your carrier.

Take care.