To install ROOT locally, go to: https://root.cern/install/
Download the latest version for your operating system and follow the isntallation instructions.
Once everything is installed, try it out by typing root into the terminal. If everything is installed correctly you should see: root[0]
ROOT is now waiting for user input. To exit: Type .q
Typically, ROOT (similar to Python) is an interpreted language and reads code line-by-line instead of compiling it all together. So you can program within the terminal by passing in lines of code:
root[0] int x = 1
root[1] int y = 5
root[2] x + y
ROOT should have outputted (int) 6. This is pretty tedious to do though and is only useful when doing quick things. Instead, ROOT typically uses “macros”, which are just files of C++ code read in line-by-line.
The most direct way of learning ROOT is looking through the manual.
A helpful resource that you’ll likely need frequently is the ROOT reference guide. Easier though is to just Google the class you’re looking for (e.g. “th1 root”). These pages give a description of classes and their member functions.
The User's Guide and Primer are also helpful references.
This tutorial gives some practice assignments that increase in complexity and difficulty. Solutions are also provided -- .cpp files for code and .txt files for answering questions. If you have any questions, please feel free to contact me or shoot me an email at rmilton@ucla.edu .