how to make my computer work

when i turn on my computer, it ask me a password. but i haven’t set a passwork. maybe my kid did it. without the password, i can’t do anything with my computer. i look for a solution on web, at last, i found one. i don’t understand what it means. it doesn’t show me step by step how to make it work. i think that solution just for the people know more about a computer than the people like me. hope have someone can help me. thanks so much.