Upgrading of iPhone
Please show me how to upgrade my iPhone because I want to upgrade it to the new version
Assuming you have a compatible device, see: Update your iPhone, iPad, or iPod touch - Apple Support
And: If your iPhone, iPad, or iPod touch won't update - Apple Support
If the above Apple articles do not help, please post back with relevant information.
EDIT: Can we assume that you have already solved your issue?