How to take whatsapp backup (from Phone Memory to Sd Card) on Android
You just need to copy the WhatsApp folder from your internal sd card (/sdcard) to your new phone. If you then first launch WhatsApp it should ask if it should restore your messages.

Note: This only works if you use the same phone number on both devices. For more information about that see the WhatsApp FAQ: http://www.whatsapp.com/faq/en/android/20887921