Hello: Take a look here:
Go to Settings>iTunes & App Stores and sign off of the old account, then sign on with the new ID. Also, under Settings>iCloud, if the old ID is still signed on, then delete the iCloud account and sign back on with the new ID.
Remember, all apps purchased under the old ID will still be tied to that old ID, so when they need to be updated, it will ask you for the password to that old ID. It is easiest if you go into Manage Your Apple ID, and under that old ID, update your password to match the one you are using for your new ID.
Also, the iCloud account associated with your new ID will not have any of your photostream or other iCloud information from your old ID, unless you simply changed your old Apple ID, rather than if you created a new ID.
~Katana-San~