There are many different designs and variations of handlebars. Comparing to your existing bars is a great way of upgrading if you are happy with your current design/shape type. And don't forget to read the Wiggle customer reviews for feedback on products.
Road bars are curved to offer a multitude of positions to suit the terrain. When climbing in the saddle you will often ride on the tops which are the part of the bar either side of the stems clamping point. When out of the saddle on climbs or accelerating you will often ride on the lever hoods mounted at the front of the bars curved section. For higher speeds you will find yourself on the drops, which offer a lower more aerodynamic position. Road bars come in a variety of widths, from 36cm wide up to 44cm, a good guide for bar width is your shoulder width, a bar should not be narrower than your shoulders as this can close up your chest, but they should not be so wide that you are creating a large frontal area. Road handlebars come in two clamp sizes, 31.8mm which is oversized and 26/25.8mm which is standard, it is essential that you get the correct clamp size for your stem as a poor fit will slip round. Road bars also come in different shapes and depths, with various bends for ergonomic reasons, some will also feature grooves in the material for your brake and gear cables to slot into, this helps to keep the bar round once tape is applied. Then there is the all-in-one bar and stem systems from brands such as Cinelli's Ram 2 and the Pro Stealth which offer clean lines and look great with their exposed carbon finish.