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 Vehicles tab just to the right. You will see the vehicle information that is attached to your account. If you want to add a vehicle, click the +Add Vehicle button and add the pertinent information.
If you need to Re-Upload Documents for your current vehicle, click the Re-Upload Documents button to the right of your vehicle.