Showing Up for Racial Justice (SURJ) is an organization which provides ways for white Americans to get involved with the fight against racism. As they put it,
Through community organizing, mobilizing and education, SURJ moves white people to act as part of a multi-racial majority for justice with passion and accountability. We work to connect people across the country while supporting and collaborating with local and national racial justice organizing efforts. SURJ provides a space to build relationships, skills and political analysis to act for change.
At their website, you can get access to anti-racism resources and learn about opportunities to volunteer or organize in your local area.