Documenting GêBR is an on going project. To quick start, read the install instructions. The FAQ page gathers common doubts. Some information is also in the GêBR discussion group. The interface itself is documented in the GêBR user guide. However, each flow component available inside GêBR has its own documentation.
GêBR can be extended by porting command-line oriented programs to it. This is done through another dedicated interface, DéBR. Documents below guide beginners into porting-programs task.