how to use GPIO ??

1. install recalboxOS-4.0.0-beta5.zip
2. boot
3. putty connect my raspberry pi
4. login as : root // root@192.168.1.31's password: recalboxroot (enter)

5. <- show my display

6. type (https://github.com/recalbox/mk_arcade_joystick_rpi)
   mkdir mkjoystick
   cd mkjoystick
   wget https://github.com/digitalLumberjack/mk_arcade_joystick_rpi/releases/download/v0.1.4/install.sh
7. type
   sudo sh ./install.sh updatesystem
8. show error
   -sh: sudo: command not found

How should the problem be solved