Hello sir....start with cardio and light weights....more of cardio ....initially.....as you start loosing weight.....you can increase your weight exercises. Reason behind it .....in obese person the efficiency of muscles is less because of accumulated fats.....cardio helps to burn your fats. As fats in body decreases....muscle efficiency improves. If you do more of muscles initially, you will experience more of muscle fatigue and strain, than there are high chances of giving up exercises. So initially concentrate on cardio more.