Use the same malt you made you beer with. Otherwise brown sugar works well, you can get that at the supermarket. I dont think you can get the malt you will need at the supermarket. Use 1/2 cup brown sugar for a 3 gallon batch. 2/3 for a 5 gallon batch, You probably know already but boil a cup of water or so, disolve the sugar let it cool, poor into your bucket, siphon beer into with a gentle stir and you should be good to go. Just be sure your beer is done because with residual sugar still in your brew, along with priming sugar you might have a bomb on your hands. I have never primed with malt, So I cant answer that one.