Hi, welcome to the forum.
When the project is powered on, how do you know where the stepper motor is ?
The Arduino Stepper library: https://www.arduino.cc/en/reference/stepper.
Start with this library.
The AccelStepper library: https://www.airspayce.com/mikem/arduino/AccelStepper/
A switch bounces, you need something to debounce the switch. There are a number of good libraries for that.
To detect the moment (the event) when a switch is closed, you need the State Change Detection: https://www.arduino.cc/en/Tutorial/BuiltInExamples/StateChangeDetection.
Some debounce libraries have also the State Change Detection included.
Can you make a first sketch ? Put it between code tags and show it.