How to use an Edge Scraper och Paper Distressing tool. OK, I did trow in a pair of scissors here too, see what you think!
They all (should) do the same – scrape / distress the edge of your paper.

As you can see I prefer to turn my paper so the backside is UP when I use the tools. I think it looks nicer from the front then.
Leave as is, chalk your edges or put some gesso along the edge when you are done. Gives you different effects – try to find out what you like.