How do I tell my mom, dad, & stepmom I got my period?

Well I got my period on Valentine's day and it didn't like get my underwear dirty or anything so I swiped a pad from my dad's & stepmom's bathroom cuz I thought it was a period but I wasn't sure & I'm glad I did. But now I hav 2 tell them cuz I live with them, then I see my mom every weekend so how do I tell her? Oh and how often do I need 2 change pads?