Check out this great VizWiz tutorial video (with video description) created by folks at the University of Maryland Baltimore County:
There are three main steps to using VizWiz Social - preparing to use the application, recording a question, and receiving an answer.
When you start VizWiz for the first time, you need to make sure that your phone is connected to the internet using either wifi or the cellular network. Once you have a connection, you can open the application and begin to record a question).
From the home screen of the application, you can begin recording a question. This involves three steps - taking the photograph, recording the audio, and choosing a destination for your question. Remember when choosing the destination for your photo that some services involve sending your photo to anonymous web workers. We advise you not to send any photos that you would like to remain private to these services.
Finally, you need to choose the destinations for your question. The services you can send your question to are listed in more detail on the About page. Remember that if you choose to send your question to either "Web Workers" or "IQ Engines", anonymous people on the web might see the photo you take. For that reason, we advise against taking any personally-identifying photographs, pictures of people, or other pictures that you would want to remain private.
Navigate through the toggle switches for the anonymous workers, object recognition software, and your Twitter account, and doubletap the switches if you want your question to be posted to that service. For Twitter, if the toggle switch is turned on, two new fields will appear where you can type your username and password. To send your question to a contact's email address, navigate to the "Email" button. Hitting this button will bring you to your iPhone's address book. Select the email address of the contact to whom you want to send your question. Once you have made your selections, nagivate to the button labeled "Send Button".
At any point during this process, you can navigate to a button that allows you to return to a previous screen and redo that step.
Once your query has been submitted, you can either wait on the "View Answers" screen or leave the app and restart it to check for answers. When on the answer screen, the phone will say "New answers available", and you can navigate down to those answers. If the answer is unsatisfactory, you can keep waiting and VizWiz will continue to alert you when answers are received.