diff --git a/INSTALL b/INSTALL
index 983990e..c83edc6 100644
--- a/INSTALL
+++ b/INSTALL
@@ -1,3 +1,8 @@
-Installation steps should be found on http://www.dugwood.com/clickheat/installation.html
+Install it via Piwik Marketplace.
 
-La description de l'installation devrait se trouver sur http://www.dugwood.fr/clickheat/installation.html
+This plugin installer will make directories:
+
+    yourpiwik/tmp/cache/clickheat/cache
+    yourpiwik/tmp/cache/clickheat/logs.
+
+This plugin uses a different tracker. Please click on the link "JavaScript" and put the special Javascript codes into your website.
diff --git a/README.md b/README.md
index 881a5df..e0931fa 100644
--- a/README.md
+++ b/README.md
@@ -28,11 +28,15 @@ __And what functions are not included in this feature ?__
 
 __Where is the coordinate information from the browser ?__
 
-ClickHeat plugin uses text files to record the coordinate data of each browser in directory: yourpiwik/tmp/cache/clickheat/logs. 
+ClickHeat plugin uses text files to record the coordinate data of each browser in directory: yourpiwik/tmp/cache/clickheat/logs.
 
 __Does it withstands high traffics ?__
 
-Unfortunately not. Because this plugin uses text files to record data. Therefore, please use this plugin to experiment or low traffics.
+This plugin uses minimal text to record data and file based logging. And when click.php is called from a special Javascript for cgi, just append text on end of the each file. And when you analyze the click data and make a heatmap, plugin will create cached heatmap as png image file. 
+
+Therefore, we expect the plugin light works, but we don't know what load it has under Piwik 2.x. So we are very glad, when you inform us about your situation. 
+
+Please see the link [Performance and optimization](http://www.labsmedia.com/clickheat/156894.html) about system resources. If you want performance, you need to avoid to use a cgi, that is possible. It method is explained on the link. 
 
 __New click data were added, but not updated heatmap. Why ?__
 
@@ -40,7 +44,7 @@ Plugin places heatmap images in the cache directory: yourpiwik/tmp/cache/clickhe
 
 __Showed a heatmap, but not overlay a heatmap to the target web page. Why ?__
 
-Check that your website does not set the HTTP header __X-FRAME-OPTIONS__ to __SAMEORIGIN__ as this will prevent this plugin from iframing your website for the heatmap report. Please see [Page Overlay Troubleshooting](http://piwik.org/docs/page-overlay/#page-overlay-troubleshooting), that is same problem. 
+Check that your website does not set the HTTP header __X-FRAME-OPTIONS__ to __SAMEORIGIN__ as this will prevent this plugin from iframing your website for the heatmap report. Please see [Page Overlay Troubleshooting](http://piwik.org/docs/page-overlay/#page-overlay-troubleshooting), that is same problem.
 
 ## Changelog
 * 0.1.0 First beta
diff --git a/plugin.json b/plugin.json
index eef1957..8513e2d 100644
--- a/plugin.json
+++ b/plugin.json
@@ -5,7 +5,7 @@
     "theme": false,
     "keywords": ["clickheat", "heatmap", "dugwood", "piwikjapan", "yamachan"],
     "require": {
-        "piwik": ">=2.12.1"
+        "piwik": ">=2.11.1"
     },
     "license": "GPLv3 or later",
     "authors": [
@@ -15,7 +15,7 @@
             "homepage": "http://www.dugwood.com/clickheat/index.html"
         },
         {
-            "name": "yamachan(a member of PiwikJapan)",
+            "name": "yamachan (a member of PiwikJapan)",
             "email": "yamachan@piwikjapan.org",
             "homepage": "http://www.piwikjapan.org/"
         }
diff --git a/screenshots/Your_heat_map.png b/screenshots/Your_heat_map.png
new file mode 100644
index 0000000..24af31d
Binary files /dev/null and b/screenshots/Your_heat_map.png differ