diff --git a/src/README.md b/src/README.md
index 29f340e1f259c9566529d369e6e9dc3923058a8d..83dbc1abd2d115be8113a0c32f3ad000330cac52 100644
--- a/src/README.md
+++ b/src/README.md
@@ -7,3 +7,27 @@ This directory collects the source code of the original programs and the develop
 The original code is contained in the folders named `cluster`, `sphere` and `trapping`. Each folder contains a `Makefile` to compile either the whole program set or the single programs. A global `Makefile`, which contains instructions to build all the original source code, is available directly in the `src` folder.
 
 In all cases, build commands executed through `make` will output the object files and the linked binaries in the proper folders under the build directory.
+
+## FORTRAN code setup and execution (requires `gfortran` and GNU `make`)
+
+1. cd to the `src` folder
+2. run `make`
+
+   > make
+
+3. cd to the `build/sphere` folder
+4. run `sph` following the instructions given in `build\README.md`
+
+## C++ code setup and execution (requires `g++` abd GNU `make`)
+
+1. cd to the `src` folder
+2. run `make np_sphere`
+
+   > make np_sphere
+
+3. cd to the `build/sphere` folder
+4. run `np_sphere`
+
+   > ./np_sphere
+
+5. check the consistency between the text files named `OSPH` and `c_OSPH`