To line a baking pan with parchment paper, cut a piece of parchment paper that is 3-4 inches larger than the pan. Press the sheet down firmly into the pan and run your finger along the base along each edge to crease the parchment so it stays. Fold the edges back over the top rim of the pan as best as you can. It won't be perfect but will keep the brownies from sticking! You can use metal clips along the top rim to secure the parchment paper to the pan if you have them but don't use plastic or they will melt in the oven.