added instructions to restore nuget packages

Author: Jonathan

HOL.md

@@ -81,6 +81,12 @@ The new version of ASP.NET Web Forms introduces a number of enhancements focused
 In this task, you will discover the new strongly-typed bindings available in ASP.NET 4.5.
 
 1. Open **Visual Studio 2012** and open the **WebFormsLab-Ex1-Begin.sln** solution located in the **Source\Ex1-ModelBinding\Begin** folder of this lab.
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+1. Click **Project** and select **Manage NuGet Packages**.
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+1. In the **Manage NuGet Packages** page, click **Restore** in order to download missing packages.
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+1. Build the solution by clicking **Build** | **Build Solution**.
 
 1. Open the **Customers.aspx** page. Place an unnumbered list in the main control and include a repeater control inside for listing each customer. Set the repeater name to **customersRepeater** as shown in the following code.
 
@@ -585,6 +591,12 @@ Forms with complex data including validators tend to generate too much JavaScrip
 In this section, you will enable unobtrusive validation in ASP.NET to compare the HTML code generated by both configurations.
 
 1. Open **Visual Studio 2012** and open the **WebFormsLab-Ex2-Begin.sln** solution located in the **Source\Ex2-Validation\Begin** folder of this lab. Alternatively, you can continue working on your existing solution from the previous exercise.
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+	1. If you opened the provided **Begin** solution, you will need to download some missing NuGet packages before continue. To do this, click **Project** and select **Manage NuGet Packages**.
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+	1. In the **Manage NuGet Packages** page, click **Restore** in order to download missing packages.
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+	1. Finally, build the solution by clicking **Build** | **Build Solution**.
 
 1. Press **F5** to start the web application. Go to the Customers page and click the **Add a New Customer** link.
 
@@ -909,6 +921,12 @@ In this exercise, you will be introduced to the new asynchronous page processing
 In this task, you will update the product details page to allow the user to specify an image URL for the product and display it in the read-only view. You will create a local copy of the specified image by downloading it synchronously. In the next task, you will update this implementation to make it work asynchronously.
 
 1. Open **Visual Studio 2012** and load the **WebFormsLab-Ex3-Begin.sln** solution located in **Source\Ex3-Async\Begin** from this lab's folder. Alternatively, you can continue working on your existing solution from the previous exercises.
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+	1. If you opened the provided **Begin** solution, you will need to download some missing NuGet packages before continue. To do this, click **Project** and select **Manage NuGet Packages**.
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+	1. In the **Manage NuGet Packages** page, click **Restore** in order to download missing packages.
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+	1. Finally, build the solution by clicking **Build** | **Build Solution**.
 
 1. Open the **ProductDetails.aspx** page source and add a field in the FormView's ItemTemplate to show the product image.