Insufficient info need win rate and risk to reward to calculate position size at the bare minimum kelly crieteria tells the mathematical optimum position size for a given win rate and risk reward use 1/2 kelly or less as kelly is too aggresive for most.
It would be unwise to put all your eggs in one ES basket so I agree with the poster that said 10, but if play is diversified and on longer-term, 100 contracts is my normal