Am I on my period

I just got this app cause I turned 12 recently and this morning there is really dark brown stuff on my undies. Is that my period or did I poop or something I don't know. I'm living with my dad and brother so I'm not asking or talking about it with them. I don't even know if it's my period! But I looked up some stuff on google but I am still a bit confused. If it is my period how do I tell my dad that I need pads or something? Help!!