My first league ever some guidance on my copy pasta CoC nova

hey , This is my first league ever playing Poe properly
When I had a mirror drop i was able to buy some decent gear and I tried following Eseros CoC nova ass but I've been struggling with Meta and certain bosses oneshotting me.

Is there any advice on what gear upgrades I could get at this moment and what skills I'm doing wrong or health nodes i should go for ?

https://pastebin.com/4QJSMD6W

dont know how path of building works yet but on the gem slot to the templar tree I've got a Glorious Vanity gem with the nodes around it giving me a total of 103% cold damage 0.4 cold damage leech and 26% increased spell damage and 39% increased spell crit chance 4% attack speed 4%max life and 5% max energy shield and 10 cold resist

I'm rly lost with defensive gems since i found steelskin to be barely a fart in the wind defensive wise

Forgot to mention I would like to get
52%-57% Cooldown reduction <10 aps

into my build but I have no idea how to read Path of building and finding out what my real aps is or my total cooldown reduction