These are all in the Ultimate Team mode.
There are 10 tasks in the first GM Objective:
Win a fantasy challenge game with no entry requirements
Apply a contract to a player
Post an item to auctions
Buy an item from Auctions with no Buy Now Price (it cannot have one listed at all)
Build an all-silver team (either stock up you team OR buy PG's if you can for Level 2)
Change your team name (you can change it and go right back)
Change your venue (you can change it and go right back)
Change your home or road jersey (you can change it and go right back)
Win 10 games in NBA Live Ultimate Team
Win a fantasy challenge with entry requirements
Complete a head to head game (I played, someone quit in about 2 mins and this counted)
I added comments to some of these so that they were easier to understand and get.