HI Elizabeth Malloy. From my understanding, the types of exercises that you will want to focus on are exercises that will draw the abdominal muscles closer together and decrease the size of the diastasis recti. In addition, you should avoid any intense abdominal or core exercises. Before starting any exercises, I highly recommend you consult with you doctor to ensure that these exercises won't cause any further harm and that you are doing them correctly.
While Grokker does not have any videos specifically focusing on diastasis recti, I've attached some that may help. Again, please verify with you doctor that these exercises are suitable for you.