The "Girls Who Code" program was created because of the discrimination and bias women face in the tech industry (not to mention other workplaces and areas of life). Also, the existence of woman managers doesn't suddenly mean that sexism doesn't exist in the industry. I'd imagine that many woman managers have faced a lot of prejudice throughout their careers. And there's probably a large amount of women who want to get into technology, but are intimidated by the space and fear potential sexism.

Also, the reason that running a "boys club for computers" or a "men's IT society" wouldn't end well is because men already make up a large portion of the tech space and, like I said, there's a lot of gender bias in the tech world. This comment comes off as you using anecdotal evidence to disprove the marginalization women face.