Create a VisualStudio project, in the template, select Word2010 Addin:
Word 2010 addin template: Application-level add-ins
Word 2010 document: Document-level customizations
Add a new user control “DemoTaskPaneControl” to the project, and add some controls to it.
Add the code below to the ThisAddIn_Startup() function
Compile and run the project, and you will see a new taskpane shown in MS Word 2010.
To disable the addin in MS Word 2010, go to File > Options > Addins > Manage, and unslect the addin project:
That is it.