Question

Go to the Teambuilder page and follow the steps to create your team, once you are happy with your work, go to the game and search for your creation

At least I believe thats how it works have it done it myself.

Teambuilder doesn't work with offline dynasty ( for some braindead reason )..much like most the game actually ( sliders, wear & tear, cpu scount/roster logic, coaching carousel that was "supposedly rebuilt" but is the same as last year ) 

Note that the teambuilder won't work if you are in game. You legit have to close the game out in order to work on the teambuilder bage.