Better documentation

Author: sapher

README.md

@@ -1,3 +1,66 @@
 # youtubedl-java [![Build Status](https://travis-ci.org/sapher/youtubedl-java.svg?branch=master)](https://travis-ci.org/sapher/youtubedl-java)
 Just a simple WIP java wrapper for youtubedl 
 
+## Prerequisite
+You need `youtube-dl` to be installed and available. You can follow [those instructions](https://github.com/rg3/youtube-dl/blob/master/README.md#installation) to install `youtube-dl`
+
+## Usage
+
+YoutubeDL wrapper is compose of 3 main class : `YoutubeDL`, `YoutubeDLRequest`, `YoutubeDLResponse`.
+
+### YoutubeDL
+Static class that execute a request and return a response.
+
+#### Execute a command
+
+```
+YoutubeDL.execute('--version');
+```
+
+#### Execute a request
+
+```
+YoutubeDLRequest request = new YoutubeDLRequest();
+YoutubeDL.execute(request);
+```
+
+### YoutubeDLRequest
+Represent a command for youtube-dl to execute.
+You can **set** and **get** all options handle by youtube-dl : [YoutubeDL Options](https://github.com/rg3/youtube-dl/blob/master/README.md#options).
+
+```
+// Example to set / get rate limit
+request.setRateLimit(1024);
+request.getRateLimit();
+```
+
+### YoutubeDLResponse
+Represent the result of a request.
+
+This object is composed of:
+
+* **exitCode** Exit code of youtube-dl programm
+*  **err** String from stderr
+*  **out** String from stdout
+*  **directory** Directory where the programme has been launched
+* *more useful to come...*
+
+## Custom request
+
+You can use `YoutubeDLRequest` object to build any  command you want.
+
+```
+// Download a video
+YoutubeDLRequest request = new YoutubeDLRequest();
+request.setUrl("https://www.youtube.com/watch?v=dQw4w9WgXcQ");
+request.setDirectory("/Users/johndoe/Desktop");
+YoutubeDLResponse response = YoutubeDL.execute(request);
+
+// will result to youtube-dl https://www.youtube.com/watch?v=dQw4w9WgXcQ
+```
+
+Be care, you can build a nonsensical command.
+
+### Links
+
+[YoutubeDL Documentation](https://github.com/rg3/youtube-dl/blob/master/README.md#installation)