If You Know How To Do This Then That's Good , Im Just Showing The People Who Don't Know How To Do It.

Tutorial :

Step 1 : Start Off At The Menus & Go To Create Player Then Create Your Player

Step 2 : Put Your Created Player On The Team You Want Him To Be On

Step 3 : Now Go To Create Team & Create A Team ( Skip Through The Customizations & Stuff
And Just Go To The Part Where You Draft Players To Your Team )

Step 4 : While Your In The Part Where You Draft Players To The Created Team Go To The
Team That You Put Your Created Player On & Select Everyone From That Teams
Roster Onto Your Created Team

Step 5 : After Your Finished Creating Your Team Make Sure Your Roster Is Saved

Step 6 : Go Back To The Menus & Start A New Season Then When You Get To The Season Options
Menu Go Down To Customize League & Switch It To On Then Start Season

Step 7 : After That You Should See A List Of The NBA Teams. Look In The Conferences &
Switch Out 1 Of The Teams For The Created Team You Made. ( Name Should Be TEAM )

Step 8 : After That Select Your Created Team To Play As In The Season

Step 9 : Once You Get To The Season Menus Quit Out Of The Season & Go Back To The Regular
Menus

Step 10: Go To Roster Then Trade Your Created Player From The Created Team You Made For
Your Created Player That You Have On The Team You Want To Be On ( Just Swap Em )

Step 11: After That Go To Create A Legend Mode & Go The Team You Put Your Created Player
On & You Should See You Can Play As Him

You Welcome !