If theyre shaking all the time, then tu need to see your doctor cos theres no way someone can tell tu without seeing you, because there are lots of things it could be. It's probably nothing, but something called Parkinson's Disease is associated with shaking hands, however it only normally affects old people. tu should see your parents and explain it to them, then go to the doctor when tu have time, to put your mind at rest.
My hands sometimes do that. It's annoying when I'm escritura o something, my escritura goes messy xD Don't worry it's probably nothing, but if it carries on for más than a day, tu might wanna get it checked out.