In the test explorer in Visual Studio there should be a button that has three lines with circles on the left side of the lines and arrows on the right sides (if you hover over it it says 'Run Tests in Parallel'). Make sure this is checked (its background will be a different colour to the test explorer panels when selected).
For each test you want to be parallel add the attribute Parallelizable. So the thing above your method that looks like [Test] will become [Test, Parallelizable].
Extra - This doesn't apply to you but will apply to a few people so I'll add it. If your Driver is a static instance (like a Singleton) you need to annotate it with [ThreadStatic] or else the different tests will all be called on the same driver.
