Hello year old post, interesting to see you here.
Help with what exactly? Hiding supplies? Most witches supplies are simple things like notebooks and candles. If its something major like your book of shadows or athame I suggest investing in a cabinet with a lock. While my family knew I was Wiccan, I had a filling cabinet with a lock which I stored my supplies. I got it from IKEA for, like, 60$ Canadian so you could ask to buy one for school work, and keep the items inside.
If you want to tell your parents, keep calm, wait for the right moment and explain giving key reasons why this path is right for you. Be sure to provide books, websites, and other information for them. If they say no, don't argue, just ask them to think about it, and ask a week later if they had a chance to read the information. You might have to meet half way.
Anything specific you need?