Update instructions related neo.smartcontract.framework and change …

…the sample contract to the HelloWorld example (neo-project#485)

en-us/sc/quickstart/getting-started-csharp-mac.md

@@ -12,31 +12,38 @@ Just check the basic functions when installing, without selecting the platform s
 
 ![](../../../assets/mac3.png)
 
+### 2. Building NEO smartcontract framework
+Unlike on Windows where they can get the `Neo.Smartcontract.Framework` via `NuGet`, on OSX we have to compile it ourselves or step 6 (see below) will fail when using any of the NEO smartcontract specific methods.
 
-### 2. New Project
+Download [neo-devpack-dotnet](https://github.com/neo-project/neo-devpack-dotnet) from GitHub. Open `neo-devpack-dotnet.sln`. You might receive errors about "Unknown solution item type" for the Installer and 2 Template projects, these can be safely ignored. Dismiss the warning dialog and right click on the `Neo.Smartcontract.Framework` project, choose `Build`. Note the location where the `Neo.Smartcontract.Framework.dll` is saved, we will need this location in the next step. i.e.
+```
+<neo-devpack-dotnet download folder>/bin/Debug/netstandard2.0/Neo.SmartContract.Framework.dll.
+```
+
+### 3. New Project
 
 Open Visual Studio for Mac，create a new project, and select .NET Standard Library（.NET Core → Library）。
 
 ![](../../../assets/mac4.png)
 
 > [!Note]
-> When you create a new project, select 2.0 for the .NET Core version，because if you select 1.x ，then adding “Neo.SmartContract.Framework” will fail.
+> When you create a new project, select 2.0 for the .NET Core version.
 
-Next, right click on the project，click `Add NuGet Packages...`，search for “neo”，select “Neo.SmartContract.Framework”，and click on `Add Package`。
+Next, expand the project，right click on `Dependencies` and choose `Edit references...`. Go to the `.NET Assembly` tab, choose `Browse` and add the `Neo.Smartcontract.Framework.dll` from the location saved in Step 2. 
 
 ![](../../../assets/mac5.png)
 
-After the installation is successful, write the following sample code in your Class1.cs file.
+Check the checkbox and press ok to close the dialog. Next, write the following sample code in your Class1.cs file.
 
 ```c#
 using Neo.SmartContract.Framework;
 using Neo.SmartContract.Framework.Services.Neo;
 
 public class Class1: SmartContract
 {
-    public static bool Main()
+    public static void Main()
     {
-        return true;
+        Storage.Put(Storage.CurrentContext, "Hello", "World");
     }
 }
 ```
@@ -45,7 +52,7 @@ In the menu choose `Build`，`Build All` to compile the corresponding code. A .d
 
 In the example the contract is named `sample_contract`. After compilation the file `sample_contract.dll` is created that we'll use in the next section.
 
-### 3. neo-compiler
+### 4. neo-compiler
 
 Download [neo-compiler](https://github.com/neo-project/neo-compiler) from GitHub. Before opening the solution in Visual studio we first have to edit the `neon.csproj` to alter the runtime identifiers. Locate the file at `/neo-compiler/neon/neon.csproj`, open it using a text editor and replace 
 ```
@@ -58,14 +65,14 @@ with
 Next open the `neo-compiler` solution and build the project. You'll now find `neon.dll` under `/bin/Debug/netcoreapp2.0/`.
 
 
-### 4. .NET Core
+### 5. .NET Core
 
 Download and install  [.NET Core 2.0.3](https://www.microsoft.com/net/download/macos) if you haven't already done so.
 
 ![](../assets/mac8.png)
 
 
-### 5. Compiling your smart contract to .avm
+### 6. Compiling your smart contract to .avm
 
 The basic syntax is 
 
@@ -77,8 +84,8 @@ dotnet neon.dll <your smart contract.dll>
 
 ```bash
 Eriks-Air:netcoreapp2.0 erik$ dotnet neon.dll ~/Projects/sample_contract/sample_contract/bin/Debug/netstandard2.0/sample_contract.dll
-Neo.Compiler.MSIL console app v2.0.3.1
-Find entrypoint:System.Boolean Class1::Main()
+Neo.Compiler.MSIL console app v2.0.3.5
+Find entrypoint:System.Void Class1::Main()
 convert succ
 gen abi succ
 write:sample_contract.avm