what do I do to change a fuse in my fuse box

The owner's manual will tell you. If you do not have one, download one from the internet. It will tell you the fuse that controls your brake lights.

Most time the inner side of fuse panel box that you remove to get to your fuses has a chart too and brake fuses likely in interior fuse panel. Most interior fuse boxes are between door and steering wheel just under the dash above the e-brake pedal or where most e-brakes used to be before the pull levers between seat became popular.As for main fuse box under hood look for black box with a removable lid.