If you really want to help Black Americans, stop thinking of them as Black Americans (and do the same for White, Hispanic, Asian, Jewish, Indian, Middle Eastern Americans)
They are Americans.
You're not going to be able to make an impact on a group to which you do not belong, nor should you want to. There will be individual success and failures in ANY group. There are too many factors (quite apart from the quantity of Melanin in their skin) that contribute to those individual successes and failure for one specific act by you to change that.
If you're acquainted with a Black PERSON who you believe would benefit from your assistance (and is willing to accept it) then, by all means, do what you can to help that PERSON. Not as a Black Person, but as a fellow human being.