Learning to be a host, and college
There are many schools that specialize in hosting and acting, but the overwhelmingly most important asset is to have a college degree, ideally in broadcast journalism. A normal career path is to intern at a local TV station - move up as an assistant - and to get experience reporting at times few people are watching. From there you may move into becoming a reporter is a small market and continue upwards from there. Shortcuts are rare.
While we mention broadcast journalism as the best degree, any college degree is helpful. And others are nearly equally as good, for example different communications degrees, especially with emphasis in media.