In this tutorial, Kirupa Chinnathambi will show you how to optimize the keyboard that appears for the type of information a user would be inputting instead.
Windows Phone devices are pretty much entirely touch-based. While some device flavors may contain a hardware keyboard that you can use, the primary way for you to input text is by tapping on the virtual, on-screen keyboard.
There is nothing special you need to do to bring up this keyboard. Simply set focus on a TextBox element that is used to receive text input, and your on-screen keyboard will automatically appear.