How to render html content in blog postings - Rails

I am trying to create a blog.

So far i have made a namespace called blog and have posts as nested routes

namespace :blog do
  get '', to: 'welcome#index', as: '/'
  resources :posts
end

My question is how do I create and save HTML in database and render it when the user wants to view a particular post?

In other words how do I create, save and render structured content?