At the bottom of every post you will see a link that says " Promote ". Click it and a new window pops up where you can use SBD to send a post to the promoted section.

Here is a link to the promoted section of #steemmonsters. You are one of three articles in that section at current time. Not many visit that section but there are some that do so if you plan on using the feature keep that in mind before deciding how much to spend.

https://steemit.com/promoted/steemmonsters