You can join the Bridge to Bridge run and cross the finish line even if it is your first run.  If you haven't gotten to know the folks at your local specialty running store, take a field trip sometime soon, they are often experts in fit and race training.  

Visit the shoe store in the late afternoon or evening, since your feet swell during the day (and also while you run).  A weekday is often the best time to visit as the staff will have more time available to work with you.  Bring in your running shoes and talk to the folks there about your race plans and training. Tell them about any aches, pains, discomfort, or injuries along the way. Finding a shoe that fits your feet is the most important part of the visit.  Rather than opting for a particular brand listen to the staff about why a shoe best suits your needs. Be sure to get your feet measured and bring the socks you wear while running. You should always wear socks because they protect your feet from blisters, injuries and infections.  

It’s also very important to replace your shoes periodically, about every 350 – 400 miles.  Your old shoes might look like they’re in perfect condition, but the structure of the shoe breaks down over time and cannot provide the support and protection you need.  To extend the life of your shoes only wear them for walking or running, and not around town.

Start running a little more every day.  Be consistent, be patient and build up slowly.  Don’t measure yourself against anyone else, measure yourself against your last run time or distance, and aim to do a little more each time you train.  Train consistently and take one day off a week to allow your muscles to recover.