In addition to coming to Board meetings in person, any member can draft and submit an item to be considered by Board. If you would like to make a proposal, email the President (firstname.lastname@example.org) about getting on the Cabinet agenda, fill out a proposal form, and review the timeline for passing policy.
If you're serious about making a difference, this the way to go. The executives and Board members are already overwhelmed with their projects--they'll happily help you develop your ideas, but you need to be willing to work and refine your plan. It's absolutely possible though, and everyone is rooting for you.
Good luck! You can do it, I guarantee it. :)