+1 with justchillaxin1 on the vaccuum pump but keep topping up your reservoir until the new brake fluid and no air bubbles are seen coming from your calipers. Start with the left disc caliper and then do the right second.
Word of caution DOT 3, 4 and 5.1 brake fluids will damage your paintwork. Use plenty of rags to cover your paintwork and have a small bucket of soapy water handy to clean immediately if some fluid gets onto your paintwork.
FYI, Brake fluid info link below.