But since I don't have my certifications, I can't prescribe exercises outside of the YMCA.

First of all, great plan to tell as many people about your goal as possible.

There are various diets you can go on that are successful in the short term but the main problem with them is that they're successful only in the short term. These diets see a dramatic decrease in weight (particularly fat) but this fast decrease is coupled by weight regain months after the diet is stopped. Most of the diets are too unhealthy to continue for longer than a month or so. Definitely not reccommended.

Other weight loss options are pills but, just like diets, they too see rapid weight loss followed by weight gain so only work in the short term.

The more realistic option is exercise and a proper, healthy diet. This doesn't just mean going to the gym 3 or 4 times a week and cutting out the cookies and ice cream. This means changing your entire lifestyle and diet.

Limit the amount of sedentary activity you participate in each day. Take every oppurtunity you can to walk, use the stairs, just limiting the amount of inactive transportation each day. There is something called Non-Exercise Activity Thermogenesis (NEAT). It basically includes anything that isn't planned activity (going to the gym). People who have more NEAT (walking, taking the stairs, even biking to work) in their day are generally healthier and more fit than those who work out more often (at the gym) but spend the rest of their day sedentary.

Aerobic activity are great for burning calories and becoming more generally fit (includes weight loss but also cardiovascular, pulmonary health, improving the body's reaction to insulin, etc etc etc.)

Resistance training is also important. It's possible to weight train without having the goal to get bigger. You can get stronger with very little increase in muscle mass. There are also health benefits associated with resistance training similar to those of aerobic training. A couple of additional benefits are better bone and joint health, less deterioration of muscle mass as you age.

To summarize, there is no quick fix to it and the best option is a long term one. A combinationg of a healthier diet (the North American is one of the worst) thats delicious and as fresh as possible (ensures you're getting nutritious food instead of empty calories and not getting added preservatives), decreased sedentary behaviour, and increased active behaviour including walking as much daily as possible, usage of a work out centre, or just an active hobby on top of the increased daily activity. I don't consider the south beach diet to be a healthy, long term solution.