I just started yesterday. I like it so far. I am on Steam.
I have a few questions:
How to use Chat? I cannot bring up the chat window. I pressed Enter and nothing happens. Tried to reassign to Tab and still nothing.
How to use Multiplayer? I opened the panel but it seems confusing and not sure how to proceed.
Thanks
Hello welcome , tchat doestn work when you play solo campaign it’s work in multiplayer by the way .
Welcome to the forums and Grim Dawn 
You can browse the multiplayer servers or join a friends by changing the game’s settings on the main menu from Single Player to Join Multiplayer and starting your game normally.
Host Multiplayer might be the confusing panel you found and is used for creating servers.
Hello Yinia,
and welcome to the forum and grim dawn
Hey yinia you can add me to steam Gdante14CO
Funny story about your name Yinia, that was my first character name in Titan Quest, took it from Yin-Yang, Yin of course being the light, good, etc. So, with that said, cool name! She still exist in TQ, but unfortunately I lost my save file after beating TQ on Epic and started Legendary. She was almost 70 when I lost the save file. 
Was a sad day, and it still makes me sad when I try to play TQ, I had put in so many hours. Now I just have her level 48 save file, so maybe one day i will start back from there. Have fun in Grim Dawn, I have logged over 1200 hours, it is an amazing game!