The tablet PC input icon will appear in the notification area; click to launch it. You can toggle between the pen writing pad and touch keyboard anytime:
You can set the docking from settings Window:
Do not forget to check the Options in the above menu, it has lot of settings to tweak. Though the default is good enough.
During writing by pen device, you can join, delete too. The delete function is amazing, just strike through the word to delete. There will be an animated demo window on the top of the window when you click the join, delete etc. buttons to guide you: