The girl I have a crush on is ill. I want to send a message to care about her tomorrow, but I don't know how to say hello.

It's no use sending messages Now that you have a crush on someone, you have a chance to turn to the bright side. Why don't you seize this opportunity?

Buy some fruit snacks tomorrow (just don't buy anything that conflicts with her illness). Go find her! Just say you visited the patient! Do nothing, just hold a glass of water beside her and talk! Let her feel your concern!