diff --git a/src/main/java/org/scribe/builder/api/DefaultApi20.java b/src/main/java/org/scribe/builder/api/DefaultApi20.java
index d4352fe..6e03567 100644
--- a/src/main/java/org/scribe/builder/api/DefaultApi20.java
+++ b/src/main/java/org/scribe/builder/api/DefaultApi20.java
@@ -1,15 +1,42 @@
 package org.scribe.builder.api;
 
-import org.scribe.model.OAuthConfig;
-import org.scribe.oauth.OAuthService;
+import org.scribe.model.*;
+import org.scribe.oauth.*;
 
-public class DefaultApi20 implements Api
+/**
+ * Default implementation of the OAuth protocol, version 2.0 (draft 11)
+ *
+ * This class is meant to be extended by concrete implementations of the API,
+ * providing the endpoints and endpoint-http-verbs.
+ *
+ * If your Api adheres to the 2.0 (draft 11) protocol correctly, you just need to extend
+ * this class and define the getters for your endpoints.
+ *
+ * If your Api does something a bit different, you can override the different
+ * extractors or services, in order to fine-tune the process. Please read the
+ * javadocs of the interfaces to get an idea of what to do.
+ *
+ * @author Diego Silveira
+ *
+ */
+public abstract class DefaultApi20 implements Api
 {
 
-  @Override
+  /**
+   * Returns the URL where you should redirect your users to authenticate
+   * your application.
+   *
+   * @param config OAuth 2.0 configuration param object
+   * @return the URL where you should redirect your users
+   */
+  public abstract String getAuthorizationUrl(OAuthConfig config);
+
+  /**
+   * {@inheritDoc}
+   */
   public OAuthService createService(OAuthConfig config, String scope)
   {
-    return null;
+    return new OAuth20ServiceImpl(this, config);
   }
 
 }
diff --git a/src/main/java/org/scribe/model/OAuthConstants.java b/src/main/java/org/scribe/model/OAuthConstants.java
index bc0010b..01b98d3 100644
--- a/src/main/java/org/scribe/model/OAuthConstants.java
+++ b/src/main/java/org/scribe/model/OAuthConstants.java
@@ -38,4 +38,7 @@ public class OAuthConstants
   public static final String HEADER = "Authorization";
   public static final Token EMPTY_TOKEN = new Token("", "");
   public static final String SCOPE = "scope";
+
+  //OAuth 2.0
+  public static final String ACCESS_TOKEN = "access_token";
 }
diff --git a/src/main/java/org/scribe/oauth/OAuth20ServiceImpl.java b/src/main/java/org/scribe/oauth/OAuth20ServiceImpl.java
index e7a2714..f957257 100644
--- a/src/main/java/org/scribe/oauth/OAuth20ServiceImpl.java
+++ b/src/main/java/org/scribe/oauth/OAuth20ServiceImpl.java
@@ -59,7 +59,7 @@ public class OAuth20ServiceImpl implements OAuthService
    */
   public void signRequest(Token accessToken, OAuthRequest request)
   {
-    request.addParameter(OAuthConstants.ACCESS_TOKEN, accessToken.getToken());
+    request.addQuerystringParam(OAuthConstants.ACCESS_TOKEN, accessToken.getToken());
   }
 
   /**