The National Organization for Women does all of the things that most interest groups do to support the candidates that it favors. A good source of information about what NOW does in this regard can be found here.
One of the most important things that NOW does is to endorse candidates. For many voters, endorsements by trusted groups are an important source of information when deciding who to vote for. NOW also gives money to support candidates' election campaigns. Finally, NOW helps staff and organize campaigns for candidates. Its staff will go out and help recruit volunteers to work for campaigns in various capacities.
By endorsing candidates, helping to fund them, and helping them find people to work on their campaigns, NOW helps the candidates that it believes will support its agenda.