What is the relevant case law in the context of an appeal?

Appointed counsel has asked this court to review the record to determine whether there are any arguable issues on appeal. (People v. Wende (1979) 25 Cal.3d 436.) Defendant was advised of his right to file a supplemental brief within 30 days of the date of filing of the opening brief. He responded with a letter, in which he contends defense counsel never mentioned a six-year sentence. Defendant states the last paper he signed was for a 12-month "Teen Challenge" program. He claims he never used the hammer for anything except breaking into cars and stores; his aunt was hallucinating the day she was attacked. He says he would like to know if there was any blood found on the hammer.