You'll want to use the steam workshop to download boards, armies, and whatever else you may need to play warhammer.
I'd suggest subscribing to DQ Age of Sigmar 3.0 in the workshop, this will provide the basic rules for the game, tokens, and a board generator to play games on. It also includes an auto dice rolling tablet which is quite handy.
For armies and models I would download this mod
https://aos-tts.github.io/Stormvault/. It provides models for all the armies as well as datacards with info from wahapedia and allows you to quickly see rules while hovering over the cursor over a model.
Hope this helps.