To upgrade a Mozy storage plan, a user typically needs to log into their Mozy account. Once logged in, there should be an option within the account settings or subscription details that allows for an upgrade. Users can review the available storage plans, which will outline the different levels of storage and their respective pricing. After selecting the desired upgrade option, users usually follow the prompts to confirm the upgrade and make any necessary payments. It is helpful to check for information regarding any potential changes in billing cycles or terms associated with the upgraded plan. For precise instructions or any specific questions regarding upgrades, it is advisable to look on the current Mozy web page for detailed guidance or additional support options.