Just want to help you gettin into that game!

First of all: Choose the multplayer button!

Campaign or skirmish is fun (a bit) and you learn the basics but the real fun is to play against humans!
Like in every other RTS game!

If you have found the online section. Wait for a lobby and join! Most of the time it is pvran´s game. Ok that is hard for a beginner, cause he is online 24/7, but you can learn, even by loosing some matches.

Pick a Infantry leader!
Infantry is strong af in this game. So take it and use much infantry.
Smoke the way to the enemy, use all greanades! Even normal nades work against tanks! Hide in wood.

Capture flags! Spread your army. Sneaky attack serveral points. (Use smoke and nades).

Use mines at your flags or on the way enemy uses.

Last point: I would recomment to check the key-buidings and remap them, so that you are fine and fast with them.

HF and win your matches!