I think @Christine instructions will probably be a lot more in depth and more comprehensive but my method was to clamp the scraper in a vice so the long edge is to the top then using a metal file give it a few passes to make sure it’s nice and flat and removed any bit of the burr then use a burnisher slightly angled downwards and I found it easier if you hold the handle of the burnisher and the end of the rod using a bit of force run it over the edge about 4/5 times in a downward motion using the length of the burnisher then check that you’ve got a little burr on the underside of the scraper if you haven’t repeat the process till you do
This is the burnisher I used to use
My method in using it was to hold the scraper with the burr on the bottom edge facing away from you, I held it as if I was trying to snap it in half, use your thumbs to bend the middle of the scraper away from then using just a small part from the centre scrap the piece you want to smooth...........😀