When you set up a blog, you are essentially creating a website that hosts your own content. This content can be written by you or by others who contribute to the blog.
When people visit your blog, they will see the posts that you have made, as well as any other posts that other bloggers have made that are related to the topic of your blog.
You are in charge of setting up and managing your blog, and you are responsible for ensuring that it is accessible to the public. You will need to create a website hosting account in order to host your blog, and you will need to configure your hosting account in a way that allows you to publish your content.
Once you have published your content, you will need to promote it in order to increase traffic to your blog.