How to start with meditation from zero?

Im the kind of person who constantly needs some sort of noise, i wear my airpods for 7-9 hours a day and constantly listen to music, videos or movies. I noticed that i can barely focus and stay present. Mindfullness is truly a skill i lack and my therapist suggested meditation. Firstly i stopped wearing my headphones everysingle minute of the day, except working out. Now i wanna try some meditating, but how? where do i start? how often and how long per session? The main goal is to gather my consciousness back and stop this never ending state of derealization my mind is in, also managing stress levels would help a lot. Thanks for any advice.