What kind of bike should I get to accomodate me?
You really seem to have two questions:

1) As a heavier person, what should I look for when buying a bike?
This has been handled a couple of times here, but the core answer is to stick with middle of the market components. If you buy low end, the components are poorly made and will break easily. If you buy high end, they will likely be ultralight, and designed for lighter riders and will break easily.

Most bikes you will find in a reputable bike shop will be sufficient. In particular, I would look for wheelsets with traditional 3-cross spoke pattern - radial laced wheels will likely have more problems under heavy load. Something like a "hybrid" or a flat-bar road bike would work, as would a hard-tail mountain bike with slick tires if you are sticking primarily to roads a paved paths.

For more information look at these questions


How to find a mountain bike that can handle a heavier rider.
What should a big guy look for when buying a road bike?


2) As a heavier person, how can I get a decent bike for under $700?
We generally don't give recommendations for specific bikes and brands because that information goes out of date quickly. That said, I would second the comment by Daniel and recommend that you look for a used bike. You should be able to find an excellent used bike that would meet your needs as a beginner for around $500 and likely less.

Take a look at this previous question:


What should I look for when buying a used bike?


If you decide you really don't want to bother with finding a used bike, I would strongly suggest you go to your local bike shop, tell them the kind of riding you want to do, and tell them your budget. Take a couple test rides, and ride a bike a step or two above your budget to get a sense of what the trade-off in price will be.