Here's a couple of questions to consider. What could make a 1000-watt amateur radio station produce a signal equivalent to a few hundred watts? On the other hand, what could make a 200-watt station propagate across the world?
Of course, it could be a variety of factors, but the mostly likely suspect is the humble antenna system. While getting on the air is not difficult, the antenna system can be quite complex, yet is generally regarded as the most important physical attribute of your ham shack. Learning a little about antenna theory is not only required for passing your ham radio license examination, but it is also important to know in order to improve your station's performance.
To get started, take a look at this document to learn more about basic wire antennas.