I made a facebook account when I was 10 and didn't tell my mom
What did you do with the account?
I told her I was sending a message to all my friends from the computer room, then later I logged in from my bedroom.
Hiding this from your parent is not good. You should not have lied to your parents about having an account, and to open one at that age is against the rules of Facebook.
Whatever. It's fine. I was 10, everyone was doing it.
It's true that lots of people open Facebook accounts while they are underage, but it is still against the rules.  There are some definite risks online, especially for young people.  Even though you didn't face any harm, you should still advise your younger nieces and nephews against doing the same thing.