add image to Property and Unit Tests Overview.

Property-and-Unit-Tests-Overview.md

@@ -5,9 +5,9 @@ Within TestCentre, you will see a collection of property and unit tests. Each ty
 
 It is worth pointing out, TestCentre uses xUnit's Test Runner for Visual Studio. This means you can use Visual Studio's Test Explorer -- which show you the project's (unit and property) tests with a G.U.I. If you are unsure what the Test Runner is, here is a screenshot of what it looks like;
 
-SCREENSHOT OF VISUAL STUDIO'S TEST EXPLORER.
+![test-explorer screenshot](attachments/test-explorer-screenshot.png)
 
-As you can see, it is a good way to determine what tests are passing and failing. On top of that, it highlights hoe the tests are organised within TestCentre.
+As you can see, it is a good way to determine what tests are passing and failing. On top of that, it highlights how the tests are organised within TestCentre.
 
 For more information about Visual Studio's Test Explorer, use the following link;