That's not too difficult. https://www.google.com/search?q=start+blog shows a lot of ways.
Indeed, your blog needs to be hosted. But on a lot of sites, that's already taken care of. Blogger.com, for example, is a Google company and it's hosted on the Google hardware. All you have to do is to create an account. And it's the same with other blog sites.
Details of SEO might depend on the platform you choose for your blog. So that's for later.
I am new here. And I want to start a blog and interest in web hosting and SEO. But apart from the basic knowledge that this is how all happening I have no idea about most of all. So can someone give me advice where should I start to learn all this?
(I have developing knowledge already)