Right now there are two big ways of promoting your content: Promoted Profiles and Promoted Posts. Both of these will deduct Flames from your balance.
Promoted Profiles - Will make your profile show up as promoted in other people's News feed. Only people that aren't already following you will see this. The flame price for this is dynamic, depending on how many other people are boosting their profile the moment you check. The lowest cost to activate this feature is 100 Flames, but if it's higher than that, we will also prolong its duration. You can find the Promote Profile button in your dropdown menu.
Promoted Posts - Will make one of your posts show up as promoted in other people's Newsfeed. Only people that aren't already following you will see these and they also show up according to viewer's preferences. The price will always start at 100 Flames but can go up, along with the number of views, depending on the number of currently promoted posts. You can find the Promote Post button at the bottom of any post you created yourself (i.e. not shared) with a blue label, or start off promoting a post as soon as you create it.
After you use it once, the label will change to "Promoted (X)" where X is the number of times you promoted the post. Yes, these can stack! Each post you promote can be found in your Timeline, in the Promoted tab. You can keep track of the number of Paid Views in the post's Engagement stats list.
If you want to see more ways to spend your Flames, be sure to check out this article!