Here are some links to help support libraries:
NATIONAL LEVEL
American Library Association's (ALA) page on Advocacy & Legislation
The ALA's Advocacy University site
The ALA's "I Love Libraries" site
The ALA's Legislative Action Center (LAC) site
The Library Journal's "Losing Libraries" site
Facebook Groups for Library Advocacy from the "Losing Libraries" site
National Children's Book and Literacy Alliance's (NCBLA) "Become an Activist" page
CALIFORNIA
California Library Association's Advocacy & Legislation page
CAPWIZ Legislative Action Center site
LOS ANGELES
"Save the Library" site for the Los Angeles Public Library system
CALIFORNIA SCHOOLS
California School Library Association's (CSLA) Toolkit for Advocacy and Action
Mrs. Nelson's Bookstore's "Support School Libraries" page