1.) Sign up for Paystack https://dashboard.paystack.com/#/signup or Login https://dashboard.paystack.com/#/login

2.) Go to "Get Started" (1) and copy "Test Public" to "Paystack Public Key" and copy "Test Secret" to "Paystack Secret Key" (2)

"Paystack Public Key" and "Paystack Secret Key" located in the admin panel, section "Payments Settings"

3.) To exit the test mode and activate real payments - activate payments (button "Activate business" (3) in the picture above)