Mica, yes, I would at least tell your parents because this could be something serious, although it may not be. Have you ever been told you have hemorrhoids? Do you have any type of cramping, pain in the abdomen? If there is any pain, is it on one side or the other, or all around your abdomen? At the very least, please talk to a parent, older sibling, someone. You indicated this was the first time, how long ago was that? Today, Tuesday? Yesterday?
Please talk to someone. Blood in your stool is not to be taken lightly.