If you'd like to vote in the June 7 presidential primary, but are registered as "Decline to State" you must request a ballot for the election. It will not be sent to you if you want to vote in the Democratic, American Independent or Libertarian party primary.
To request a primary ballot, use the attached form which has instructions about how to fill it out. (Looks to me like you want to wait before sending in the rest of the ballot, too.)
Note: it doesn't list a mailing address where you should return your ballot request!