Q: I have purchased I phone6 but not able to use apple store

Hi there sunil@Jamnagar, 

Welcome to Apple Support Communities. 

If I understand correctly, you aren't able to use the App Store on your iPhone 6 because of an issue with your Apple ID. The article below provides a lot of great information that will resolve most Apple ID related issues, like the one that you described.

Sign in with a different Apple ID on your iPhone, iPad, or iPod touch - Apple Support

Take care.