It's Sad When You Don't Know How to Cook a Vegetable

I found this really interesting recipe in the local newspaper (Roanoke Times) on Sunday.  It was for twice-baked potatoes with fennel and zucchini and onions and cheese and it sounded really yummy.  I've never eaten fennel to my knowledge but I found one at Kroger for cheap so I was excited to get started.  Except I had no idea what the hell to do with the fennel once I got it home.  Is part of it not safe to eat?  What part of it DO you eat?  The leafy green part or the bottom part or what?  It's kind of embarrassing that at my age I have no idea what to do with a vegetable.  I had to resort to a You Tube video to teach me.  In fact, I watched three videos.  Is that not sad?  In case you are curious about fennel yourself and you don't want to be kept awake tonight wondering, one of the videos is below.

P.S. - the recipe was DELICIOUS!