Watch the awesome video opposite by @MattHDGamer showing what to do as he explains. Everyone starts off with a very average team. Returning players from previous FIFA get free packs. There is a web app which starts week or so before the console release. On there you can see what your starter team is and open any of the free packs. You can trade on the web app as if you are on the full game. Create squads, buy and sell players and even do SBCs. If you login to the webapp daily before the game is released you receive daily gifts which are just small packs or coins.
If you ordered a version of the game where you get packs these are separate and will be available when you play on your console. Although the game only gives you 1 or 2 of the packs per week available to open. You do NOT get all packs to open as soon as you start the game. Also you don’t actually have to open a pack because it is there. Maybe let them build up and open them later in the year.