Roof ventilation principles are very straightforward -- a cool attic is a happy attic! You need to create a flow of air that enters the overhang of your roof through soffit vents, then flows straight up through the rafters and out through a ridge vent. To help facilitate airflow, it may be necessary to install a thermostat-controlled exhaust fan.
Installing ridge vents is a fairly aggressive project. Do not attempt this project if you are uncomfortable with heights or uncertain about your carpentry skills. Since you will be cutting the peak off your roof, this is not a project that can be left unfinished for any amount of time. Plan ahead and make sure you have all the materials you need to complete the project before weather rolls into your area. For complete, step-by-step instructions for this DIY project, watch this friendly and straightforward video tutorial.