Q: How do I download my icloud back up from itunes onto my new iphone

Restore the new iPhone using the backup from your old one.

Transfer content from an iPhone, iPad, or iPod touch to a ...

OK, so you have indicated both iCloud and iTunes backup. Those are different. Did you literally hook your old phone up to your computer and back it up to iTunes there?

If so, follow the instructions under the iTunes section. If you actually are referring to an iCloud backup, follow the iCloud instructions:

Restore your device from an iCloud or iTunes backup - Apple Support

Cheers,

GB