If your fuel injection system has a fuel rail to deliver fuel to the fuel injectors, you will ahve to remove this before you are able to remove the injectors. This is an easy job.
First, disconnect the main fuel line at the end of the rail. There may be an additional line at the other end, so remove that one, too. The fuel rail is help in place by screws or bolts, depending on your car's setup.
Remove these screws or bolts. If your wiring travels over the top of the rail, see the next step to disconnect the wiring first. With everything disconnected from the rail, pull it away from the fuel injectors. Most fuel rails are just pressed onto the injector tops, once you've removed the hold down screws or bolts it should pull away, with a little oomph.