At what age did you start or learn masturbation

I was taught by my brother’s friend when I was five to masturbate because I’ve seen him doing that and I wonder how that feels. My brother’s friend told me that something will come out in just a matter of minutes. So I watch him and I was surprised his cock suddenly ejaculates. My brother’s friend told me to do the same everyday. I still remember my sister caught me masturbating because I forgot to lock my room.