Many parts of photography can be learned by experimentation, but studying often helps you improve much faster. A good first step is to read your camera manual carefully so you understand the 7D’s controls and features well enough to use them intentionally.

A common area where outside learning helps a lot is lighting, especially flash and strobes. Several photographers find that natural light is easier to pick up by practice, while artificial lighting becomes much clearer after reading or watching experienced teachers. Learning established techniques can save a lot of frustration and produce better results sooner.

More generally, books, websites, classes, seminars, and workshops can all help when self-experimentation stops giving you new insight. Workshops are especially useful when seeing how others work in real situations matters.

So the short answer is: almost everything can be learned through trial and error eventually, but studying helps you avoid reinventing the wheel. Use both: learn the fundamentals from manuals and good instruction, then reinforce them through shooting practice.