Is the rotors on the front is easy to change ?

The Nissan Altima has floating rotors. Make sure you use jack stands and remove the tire. You will then remove the brake caliper (support the caliper with a clothes hanger to the strut spring, don't let it hang by the hose). Remove the caliper torque member or stand. The rotor can now be removed.
Install in the reverse order. The torque member or stand will need to be torqued to 144 ft. lbs. and the caliper will need to be torqued to 14 ft. lbs. The caliper piston will need to be pushed back into the bore to clear the new rotor and pads.