Hi, Janet. If your uncle's profile is not set to indicate that he is deceased, you may not be able to make any changes to it right now regarding DNA, even though you are the sole profile manager. These recent restrictions have to do with the European Union's GDPR (General Data Protection Regulation) that goes into effect on the 25th.
If his profile does indicate he is deceased you should, while on his profile, be able to go to the second menu item on the top right-hand corner, the item labeled "Goodman-2591." Hover over that and select the option labeled "DNA." Once on that "DNA Ancestors View," you'll see a button labeled "DNA Tests." Clicking that will take you to the page where you can modify existing test information for your uncle, or add information about new tests.