I am not sure what program I should start

Good news is that you have already taken the first step by getting to the gym, so give yourself credit for that. The issues you are describing with the clean and press and squat are very common for someone coming from a lot of sitting, because prolonged sitting tightens the hips and weakens the core and glutes, which throws off those movement patterns. I would start with the Core Foundation for Posture program, which builds the hip flexor flexibility, core stability, and alignment that will make those lifts click into place. Get that base solid first and you will be surprised how quickly your movement in the gym improves.