I'm 10 and on my period .Should I tell them or what

Sure! I mean if they ask. If the conversation starts about that kind of stuff go ahead(:

That you started you period is a private matter. There is no reason to tell anyone but your mother and doctor.

If a friend asks, then you have to decide whether to tell the friend or not.

It's your choice I'm ten and my parents think that I've started too.us but all I had was brown discharge for like three days I'm not sure it was my period

It's a private matter. There is no need to tell others about your personal hygiene.