The best way to update wrought iron stair railings is by painting them. Wrought iron is a very sturdy material, so it can handle most types of paint without any problems. You will want to use a high-quality exterior paint in order to ensure that the railing lasts for a long time. Make sure to follow all of the manufacturer's instructions when painting your railing, and be sure to wait for the paint to dry completely before using the stairs.

The first step would be to remove the old railing. This can be done by unscrewing it from the wall or cutting it off with a saw. Once the railing is removed, you will need to measure and cut the new railing to size. Make sure that the new railing fits snugly against the wall. Once the new railing is cut to size, you can then install it by screwing it into place or welding it in place.