The first thing you will need to do is parse an HTML file.
After this, the details of how you implement how to display each part is entirely up to you. SFML provides access to text and image drawing and that's all you really need. You may need to customise the way you use it to allow for text altering mid-word, for example.
You should look into using
views to help with scrolling, although you will have to create your own scroll-bar/-control.
