Left blinker fast -- right blinker fine

My left turn signal is blinking at a very fast temp. I have no experience in car repair whatsoever and don't want to get "taken to the cleaners". I've read a few messages on other boards and have developed a few theories.

Do I just need to change the flasher? And if so, what is this? Where do I find it? How easy is it to change and how much will it cost me to do it myself?

I haven't checked any fuses yet. Should I, considering that the right blinker is still working fine?

Is there any chance this is going to be a much more serious job -- like maybe something inside the steering column that needs to be replaced?