Any advice for me where to start?

Hello! I'm 28, F, and I am plus size (136kg) I honestly don't know where to start, I've tried working out but it feels like I cannot support my own weight...

I've been having a hard time losing weight ever since I gained weight during pandemic from 90kg to 120kg.. time passes by I gained another 20kg. I've lost and gained some all through out those years. Then recently, when I cannot take it anymore, I went to a doctor and she advised me to take Tirze to aide me slow down my food intake.. from 141 kg i dropped to 136kg. That's why I'm interested to go to the gym, but Idk where to start when it comes to my diet and exercise.