[update] README with some installation guide

README.md

@@ -6,6 +6,56 @@ In order to be used in other application.
 
 ## Installation 
 
+For now, it only work on linux OS and Windows Professional, 
+and not tested on MacOS.
+ 
+In order to run it, you have to Download the CERN's Spark bundle
+and set up a working CERN's NXCALS environment. 
+See on <a href="nxcals-docs.web.cern.ch"> NXCALS Documentation</a>.
+
+You need then to export 2 environment variables for Spark & Python. 
+
+For linux (Ubuntu)
+``` bash
+export SPARK_HOME=<location_of_the_bundle>/spark-<version>-bin-hadoop<version>
+export PYTHONPATH=$SPARK_HOME/nxcals-python3-env/lib/python3.6/site-packages 
+```
+For windows into shell with admin rights
+```shell script
+setx SPARK_HOME <location_of_the_bundle>/spark-<version>-bin-hadoop<version>
+setx PYTHON_PATH %SPARK_HOME%/nxcals-python3-env/lib/python3.6/site-packages
+```
+Then install pyspark packages on python if not already done.  
+```shell script
+pip install pyspark
+```
+
+Maybe you would have to replace the nxcals-jars directory with the 
+one you can find into the bundle at `<bundle_path>/nxcals-jars` and also 
+the nxcals-hdoop-pro-config<version>.jar that you can find at
+`<bundle_path>/jars/nxcals-hadoop-pro-config-<version>.jar`.
+
+Know that all the links and directory path are up to date at the time of writing.
+It may have been some updates since.
+
+After that you need to create a 'pyconf.py' file in order to create
+mysql configuration. The template is :
+```python
+mysql = {
+    'host': '',
+    'port': '',
+    'user': '',
+    'passwd': '',
+    'database': '',
+}
+```
+
+You'll need to ask the databases info and access in order to complete this 
+configuration file.
+
+You can ask this info by creating an issue on this repo gitLab or by sending
+a mail to a manager of this project with your name, section and why you want
+to use the project. 
 
 ## Usage