I'll lend a hand so you'll be able to upgrade your QuickBooks, @az581200.

In QuickBooks Desktop (QBDT), before you upgrade, you'll have to purchase the product version you need. You can reach out to our QuickBooks Desktop support team for assistance. 

Once done, you're now ready to download and install the QBDT 2021. Before that, ensure that your system meets the minimum requirement needed to run the program. 

For your reference, please see this article: Upgrade QuickBooks Desktop Pro Plus, Premier Plus, or Enterprise.

When finished, the next step is to upgrade your company file so it works to the newer version. 

Also, here's a compilation of QBDT articles that you can browse to help you in doing your  QuickBooks tasks. 

I'm always ready to help you in case you have any other concerns about upgrading your QBDT. Feel free to leave your reply below. Have a great day ahead.