diff --git a/README.md b/README.md
index 41ce1e8ae..0660205a8 100644
--- a/README.md
+++ b/README.md
@@ -5,12 +5,9 @@
 This tool is used to generate `dom.generated.d.ts` and `webworker.generated.d.ts` for TypeScript, and `domWeb.js` and `domWindows.js` for Visual Studio JavaScript language service. The input file is the XML spec file generated by the Microsoft Edge browser.
 
 ## Build Instruction
-To build the tool, simply clone the repo, and run `build.cmd` in command line or powershell. If it runs successfully, the output files will be generated under the `generated` folder.
+To build the tool, simply clone the repo, and run `build.cmd` (Windows) or `build.sh` (OS X/Unix) in command line. If it runs successfully, the output files will be generated under the `generated` folder.
 
-## Code Structure
-- `Shared.fs`: handles the parsing from XML spec file, and stores the common data structures for later use;
-- `TS.fs`: handles the emitting of the `lib.d.ts` file;
-- `JS.fs`: handles the emitting of the `domWeb.js` and `domWindows.js`
+Note: for OS X/ Unix users, [Mono 4.2](http://www.mono-project.com/download/alpha/) is required.
 
 ## Contribution Guide
 The `dom.generated.d.ts` and `webworker.generated.d.ts` files in the TypeScript repo are used as baselines. 
@@ -21,6 +18,17 @@ For common changes, it is sufficient to change the json files.
 There are three json files that are used to alter the file generation: `addedTypes.json`, `overridingTypes.json` and `removedTypes.json`.
 The format of each file can be inferred from their existing content. 
 
+The common steps to send a pull request are:
+  0. Open or refer to an issue in the [TypeScript repo](https://github.com/Microsoft/TypeScript).
+  1. Add missing elements to `inputfiles/addedTypes.json`, overriding elements to `inputfiles/overridingTypes.json`, or  elements to remove to `inputfiles/removedTypes.json`.
+  2. Run the script locally to obtain new `dom.generated.d.ts` and `webworker.generated.d.ts`. 
+  3. Update the files in the `baselines` folder using the newly generated files.
+
+## Code Structure
+- `Shared.fs`: handles the parsing from XML spec file, and stores the common data structures for later use;
+- `TS.fs`: handles the emitting of the `lib.d.ts` file;
+- `JS.fs`: handles the emitting of the `domWeb.js` and `domWindows.js`
+
 ## Input Files:
 - `browser.webidl.xml`: the XML spec file generated by Microsoft Edge (due to the different updating schedules between Edge and TypeScript, this may **not** be the most up-to-date version of the spec.);
 - `webworker.webidl.xml`: contains additional types for webworker.