How to upgrade my iPhone?

Upgrade? Or update?

If upgrade, purchase the model that meets your needs.

If update:

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. 

Heyo, your carrier will be able to assist you in upgrading your iPhone. There are buyback programs where you give them your old iPhone for a discount on a new one. Apple also has this program directly. Happy upgrading, hope this helps! https://www.apple.com/shop/iphone/iphone-upgrade-program?afid=p238%7Cs2kS5ibit-dc_mtid_1870765e38482_pcrid_547597405660_pgrid_20984188207_pntwk_g_pchan__pexid__&cid=aos-us-kwgo-iphone--slid---product-

Go through your cellular provider to upgrade your physical phone. To update your phone go to settings>>> General>>>> Software Update