diff --git a/Selection-code.md b/Selection-code.md
index 8b4972e..ad13ba8 100644
--- a/Selection-code.md
+++ b/Selection-code.md
@@ -1,7 +1,13 @@
-The selection code is a set of C++ scripts. First, the running of the code is introduced. Then, each part of the code is explained.
+The selection code is a set of C++ scripts. First, the running of the code is introduced. Then, each part of the code is explained. The main file of the selection code is [[B2Kstmumu.cpp][B2Kstmumu]]. However, as the code required a lot of reruns and checks at different places, the main code execution became obsolete and the scripts are compiled and run in ROOT step by step. However, the file [[B2Kstmumu.pro][B2Kstmumu.pro]] can be used by the QtCreator IDE.
+
+## Setting up ROOT
+**TODO**
 
 # Running the code
-When re-running everything, do the following
+The code consists of several C++ scripts that are compiled and executed in ROOT. Before every step, it is worth closing and opening ROOT, as it is possible ROOT will complain about redefinition of functions. 
+
+We used ROOT 6.06.02. 
+
 
 First, compile and run the preselection. It is defined in [[BDTSelection.cpp|BDTSelection]] .
 ```