This looks like an important head line

By underlining text we can transform it to a Level 1 header.

This looks like a less important headline

Using a more subtle underline results in a smaller header (Level 2).

There is an alternate way to make section headers. Simply use the pound sign.

This is a level 1 header

This is less important (level2)

Level 3 header

And so on to level 6, the standard stuff available in html documents.