k first u must know wat is meant by crossover so u can do it crossover is a fast change in direction so u go in a side and then change to other side u can see iverson
first try move the ball fast from one hand to other while dribble without looking and then try wide it more and then go with ur hand and ur body not ur legs or u can use 1 leg and then turn to other side

YouTube - Allen Iverson Crossover Mix
YouTube - Allen Iverson crossover impossible
YouTube - allen iverson crossover

this 2 may help u more
YouTube - Learn how to Crossover and Pull-Up on a DIME!!! AWESOME!!!
YouTube - Learn The Crossover From Chris Douglas-Roberts

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position :PF,C
height:6.56
stand reach :8.8
run vert :14.5
2 legged jump : 13 or less
after rest for 3 weeks
run vert :24inch
2 LEGGED JUMP:23 inch