Once you have logged in to your account online, click on the menu icon in the upper left-hand corner. Select Profile. Here you will see 4 tabs at the top of the page: Profile, Manage Documents, Vehicles, Music. You will automatically be on the Profile tab. Click the Manage Documents tab just to the right.
If any document is expired, you can upload a new photo of the up to date document via your computer.
***NOTE: If you are trying to take a picture of a 'paper copy' of your license that the DMV gave you as a temporary license, that will not work. You will have to wait until you get your physical license in order to take a picture of that and upload it.
You can also do this in the Uber Driver app.
Open the Uber Driver app. On the bottom menu options, select Account. You will see a circle picture with your name under it and a blue Edit button. Click the Edit button. You will see your personal information pop up. On the 4th line down, you will see an option that says Documents with an arrow. Select that. Here you can select either the Driver's License, Vehicle Registration, Vehicle Insurance, Vehicle Inspection Form options. Take a photo of the correct document via your camera on your phone. (Make sure you allow the app to access your camera if it has not already.)