Update README.md

Author: Lukas9318

README.md

@@ -8,22 +8,71 @@ In order to run the demoanalyzer_cfg.py to create the ROOT files, you need to cr
 CMS environment. 
 
 ## Creating the Working area
-
 This step is only needed the first time.
-
-'''
+```
 cmsrel CMSSW_4_2_8
-''' 
-
+```
 ## Cloning the 2010-minimumbias-trackvertex repository from Github
-
 Type this command to change directory:
-
-'''
+```
 cd CMSSW_4_2_8/src
-'''
-
+```
 For cloning type:
-'''
+```
 git clone https://github.com/cms-opendata-validation/2010-minimumbias-trackvertex Validation/TrackVertex_2010
-'''
+```
+## Setting up the CMS environment
+```
+cd Validation/TrackVertex_2010
+cmsenv
+```
+## Compiling and Running
+```
+scram b
+cmsRun demoanalyzer_cfg.py
+```
+
+After analysis, MinBias00val.root file should be created. 
+Then, is necessary to change input and also output files in demoanalyzer_cfg.py, to save these changes and to rerun program.
+In the datasets directory in the repository from github are index files with names:
+
+```
+CMS_Run2010B_MinimumBias_AOD_Apr21ReReco-v1_0000_file_index.txt
+CMS_Run2010B_MinimumBias_AOD_Apr21ReReco-v1_0001_file_index.txt
+CMS_Run2010B_MinimumBias_AOD_Apr21ReReco-v1_0002_file_index.txt
+CMS_Run2010B_MinimumBias_AOD_Apr21ReReco-v1_0003_file_index.txt
+CMS_Run2010B_MinimumBias_AOD_Apr21ReReco-v1_0004_file_index.txt
+CMS_Run2010B_MinimumBias_AOD_Apr21ReReco-v1_0005_file_index.txt
+CMS_Run2010B_MinimumBias_AOD_Apr21ReReco-v1_0006_file_index.txt
+```
+These index files are the same as you can find in the open data portal record http://opendata.cern.ch/record/8 , they are copied here for convenience and also for details of the analysis you can read comments in the analysis code TrackVertexAnalyzer.cc .
+It necessary to note that whole analysis can take around 16 hours!
+
+When you rerun all seven index files you should have seven root files with names:
+```
+MinBias00val.root
+MinBias01val.root
+MinBias02val.root
+MinBias03val.root
+MinBias04val.root
+MinBias05val.root
+MinBias06val.root
+```
+
+The last thing what you should do is to merge these seven root files into one root file.
+You do this as follow. In the downloaded repository is also file with name mergeMinBias.C .
+Type command for opening ROOT program:
+```
+root
+```
+In this program just type command:
+```
+.x mergeMinBias.C
+```
+This merging creates a root file called MinBiasAllval.root .
+To look at this output, write down command in ROOT program:
+```
+new TBrowser
+```
+and navigate to relevant file. 
+The most interesting histograms are the inclusive track pt spectra: 2.6pt, 2.4pt... - ...0.4pt, 0.2pt  corresponding to the |eta| ranges 2.6-2.4, 2.4-2.2, ... , 0.4-0.2, 0.2-0.0