Need help to add to existing code for servo control on Ramps1.4 with Mega 2560

Hello everyone,
I wanted to know if anybody knows how to modify the code, in other words what do i need to add to the existing code ( attached with post ) if i want to use a servo ( example mg996 ) instead of the 28BYJ-48 for the gripper, and how to connect the wiring ?
Initial tests with the 28BYJ-28 are not good, the motor is very weak, and cannot turn the gear on my custom gripper design .
I am using the Mega 2560 board along with the Ramps 1.4 , currenty i have 3 stepper motors connected and 3 endstops with a 12v power supply, all seem to work well, just missing the servo

I kind of knew this would happen, that’s why i prefer to use
a servo with stronger torque ! Actually never used the 28BYJ motor, i find them to be dinky.
I know that you can connect up to 4 servos on the Ramps 1.4 board.I am only going to use one . So any feedback would be appreciated.

robotArm_v0.41 Arduino (15.9 KB)