I think your task is to work on improving both your thoughts about yourself, and your thoughts about others, learning to think of yourself as worthwhile and capable of coping with challenges, and to think of others as mostly friendly and willing to help when you need it.
You will hopefully experience both of these things with your therapist, if he or she is a good fit for you: you will experience your therapist seeing you as genuinely likeable, valuable and capable, and begin to more easily see yourself that way, too; and you will experience the gratification of receiving comfort and support from your therapist, and the security of trusting that they’re willing and able to help you– a sense that you’re going to be okay when things get tough, and learning to believe that it’s possible to get this kind of help from others as well. It may also help to think about past experiences (if you’ve had any) where you did have positive thoughts about yourself or about someone else, and remind yourself that those things really happened, and wonder if they might therefore be possible to experience again, now or in the future.