This paper presents the development and implementation of control algorithms for the Attitude Determination and Control Subsystem (ADCS) of AlAinSat-1, a 3U CubeSat. It focuses on detumbling, sun pointing, nadir-pointing, and ground contact modes. Furthermore, it discusses the mathematical models of different sources of disturbance, such as gravity gradient, magnetic torque, atmospheric drag, and solar radiation pressure. The successful implementation of the B-dot algorithm for detumbling and a PID controller for nadir-pointing is demonstrated through numerical simulations. The simulation results indicate a final spinning rate of 1 deg/s in detumbling mode, confirming the efficacy of the algorithm. The implemented PID controller effectively regulates the attitude, resulting in a 1-degree pointing accuracy during the nadir-pointing mode.