Replacing a spoke is a relatively easy repair task that most home mechanics should be able to to. If its a rear wheel the cassette may need to be removed, wheels with disc rotors may need the rotor removed. The tyre, tube and rim tape may also need to be removed to replace the spoke nipple. We have a selection of spoke tools to help you get the job done as well as a huge selection of custom cut spokes availiable in almost any length.
Once the spoke has been replaced the wheel should be checked for tension and trued, without a wheel truing stand it can be done it the frame. This isnt as accurate but you should be able to get the wheel true enough to ride.
BikeRadar have an article on how to replace spokes which may be useful for the first time spoke replacement.