Add alt text to Before the HOL guide

Hands-on lab/Before the HOL - Azure Blockchain.md

@@ -19,19 +19,19 @@ In this exercise, you will set up the necessary tools you will need to use for t
 
 3.  Click on the **Extensions** tab on the left-side of the window.
 
-    ![](images/Setup/image3.png)
+    ![Visual Studio Code window with the 'Extensions' icon highlighted in the left-side navigation](images/Setup/image3.png "Select Extensions with Visual Studio Code")
 
 4.  Type **Solidity** into the *Search Extensions in Marketplace* box, and click on the **solidity** extension authored by **Juan Blanco**.
 
-    ![](images/Setup/image4.png)
+    ![In Visual Studio Code, search for the 'solidity' extension, then click to select the extension](images/Setup/image4.png "select the 'solidity' extension within the Visual Studio Code extensions marketplace")
 
 5.  On the **solidity** extension, click **Install** to install this extension into Visual Studio Code.
 
-    ![](images/Setup/image5.png)
+    ![Select install on the Solidity extension for Visual Studio Code](images/Setup/image5.png "Select install on the Solidity extension for Visual Studio Code")
 
 6.  Click **Reload** to refresh the Visual Studio Code editor to include this new plugin for use.
 
-    ![](images/Setup/image6.png)
+    ![Select reload on the solidity extension to reload Visual Studio Code after installation has completed](images/Setup/image6.png "Select reload on the solidity extension to reload Visual Studio Code")
 
 7.  Visual Studio Code is now ready to edit Solidity (.sol) code files with syntax highlighting and other IDE features