Hi
I joined this game when it went free to play.
Initially i was placed in silver
So i was in a similar boat as you (being new to the game/not knowing what to do)
only recently i have reached diamond
In term of content creators to watch to improve i would say ML7 (good vod review series) and Emmong (good Spectating series/BINGO series)
Watching them they point out others mistakes n how to improve on them
My personal experience 
(if interested)
https://us.forums.blizzard.com/en/overwatch/t/wanted-to-share-my-rank-update-with-you-guys/871805/7