How it works...

Let's have a look at the bits and pieces and how they are bound together. From steps 1 to 7, we have opened an existing solution and added a WPF project to that solution. In steps 8 to 10, we added a control to the WPF main form, from the toolbox. Since this is a WPF application, we went through an additional element; setting up the UI. In step 11, we have set up the UI elements using the properties window. 

In steps 12 to 15, we added a reference to the WPF project. Referencing the library we have created is the most important part. Without referencing, the WPF project is totally unaware of the library.  After referencing the library only, it will available to the WPF project. Step 17 tells the compiler to use the namespace of the library. Now we don't have to call the full namespace of the class inside the library. In step 18, we created a simple variable and stored a name. The next line creates an instance of the HelloWorld class inside the library. Finally, we used the Text property of the WPF TextBlock control to store the value from the SayHello(string name) method.  

In the final steps – 19 to 20, we have executed the code and tested it.