Help with a character rererence letter?

My sister is applying for a CNA program and she needs me to write a character letter for her. Does anyone have any idea what I should put in this letter, Im clueless... Thank you
Most places want letters from people who are not related, so I'm surprised she is asking you for one! Even if the program didn't specify that, it would probably be better if she got one from someone else. Clergy, former teachers, neighbors, and friends of the family are usually the types of people one asks for these references. Sometimes former employers or co-workers too, if they aren't supplying work references. You've probably known her longer than anyone else, but a non-related reference will carry more weight.