Update README.md

README.md

@@ -1,6 +1,55 @@
 # facebook-messenger
 A most easily usable Facebook Messenger Platform API
 
+# Usage
+
+```xml
+<dependency>
+  <groupId>com.github.codedrinker</groupId>
+  <artifactId>facebook-messenger</artifactId>
+  <version>1.0.0</version>
+</dependency>
+```
+## Use FMClicent.getInstance() to obtain API Instance.
+
+```java
+ FMClient fmClient = FMClient.getInstance();
+```
+## Use with* methods to set parameters to FMClient instance. 
+
+```java
+public class FMPPostbackHandler extends FMMessagePostBackHandler {
+    @Override
+    public void handle(FMReceiveMessage.Messaging message) {
+        log.debug("FMPPostbackHandler handlePostBack, sender -> {}, postback -> {}", message.getSender(), message);
+    }
+}
+```
+```java
+FMClient fmClient = FMClient.getInstance();
+FMPPostbackHandler fmpPostbackHandler = new FMPPostbackHandler();
+fmClient.withAccessToken("token")
+        .withAccessSecret("secret")
+        .withFmMessagePostBackHandler(fmpPostbackHandler);
+```
+## Use signature method to valid the payload.
+
+```java
+StringBuilder buffer = new StringBuilder();
+BufferedReader reader = request.getReader();
+String line;
+while ((line = reader.readLine()) != null) {
+    buffer.append(line);
+}
+String payload = buffer.toString();
+fmClient.signature(payload, xHubSignature);
+```
+## Use dispatch method to dispatch payload message.
+
+```java
+fmClient.dispatch(payload);
+```
+
 # Road Map
 1.0.0
 
@@ -17,4 +66,4 @@ Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
-limitations under the License.
+limitations under the License.