I'm a fair beginner to the Pi, and have a question for the pi gods

The one thing that I find tedious when using the shell is doing "ls" after every time I do "cd". (I'm lazy)
Just wondering, how easy would it be to create a function combining cd and ls, say "cdl", that I could execute as one command?
And what file would I need to define it in?
Thanks very much for your patience with a beginner.