Really need help about to grind higher!!!!

Hello everyone, it's such a pleasure to meet all of you! It's Rei A here and it's my first time to post a thread.

Let me introduce myself:
I'm a poker fan, mainly playing Rush and Cash in GGpoker for now. Here is my question and I really need help:

I have playing 10z 25z 50z 100z before and the result is just so-so. I have been recently studied so many poker courses (mainly from grindcore and play it smart) for months and I kind of feeling like I'm able to grind higher stake like 100z in GG Rush and Cash.
But my trouble is I DON'T know if I can beat 100z for real or not. When I look all the spots played in 100z it's just feel so easy for me to handle. But to really playing the 100z make me fear and I'm no so sure I can crush them.
My first plan was to seek a private coaching from play it smart(since he's god to me so if he tells me I can do it then I will go without any fear), but he seems not available for now.

So, any advice guys? Or any method to contact play it smart? Thanks a lot to both!