Advice on GMing Cthulhu Confidential - Total newbie

Greetings! I'm a first time GM running Fatal Frequencies scenario with Vivian, everything out the box from Cthulhu Confidential with a brand new TYTRPG player. I'm struggling with a couple of things, which I think are probably blindingly obvious to an experienced GM but I was wondering if anyone's around for a chat to idiot check for me! Mostly regarding how much I should share with my player. As it's a horror and suspense ridden RPG I don't want to spoil any surprises, especially as it's their first time (there's no pressure, I just want them to have fun). If you're a fan of Notion double points. That's where I'm organising my campaign and I'm happy to share if you've already bought the game to say thanks. 

hey im a total newbie i joined about an hour ago haha uh im lookin for someone to hang out and play with, ive always wanted to play D&D so id be very existed to join (fyi im 15 so if im to young please let me know!)  

Interesting post. GURPS Horror is a must read, as wel  as the core rules. I have the Hardback and Players companion for the most recent edition, as well as here on roll20.  One of my game of thrones players is setting up to run a mini campaign of CoC in a few weeks to give me a break from forever GMing. Essentially you do not keep players in the dark, but keep them in suspense. Dread is a hook. they do not quite hear or not quite see things. I am a Call of Cthulhu GM, as well as Horror D&D, the old Tales from the Crypt, and some other fun ones like It came from the Late Late Late, Late show (which was a campy sort of send up of B movies RPG). I know of notion, but I use other campaign organizers. If you see this, perhaps we can chat on discord or similar at a time convenient for you. I've been on this site for over 10 years.  Good luck.