First period help

I think I may have just gotten my period and I'm really scared and freaking out. I went to the bathroom and when I wiped there was some red on the toilet paper and I think it's my period. I don't know what to do now. My mom and dad aren't home because they went on a business trip. I'm staying with my grandparents for the week but my grammy is out with her friends so it's just my grandpa here and I don't want to tell him. I don't know if I should call my mom or not so I found this app