Drop down menus and further organization

Hi
I made a wordpress blog which I plan on using as a “Slayer Log” for my gaming activities. (I made this just to get the hang of wordpress as I plan to make an actual blog soon) Anyway, so you can understand what I mean:
On Runescape (A game), you are assigned to kill so many npcs (non player characters). When you defeat/kill them, they drop items to be used in the game, etc etc. On my slayer log, I want to be able to have categories for each specific npc (monster) I kill, so i can go to say category one for monster a, and all the posts will be about monster a. I want to be able to record how many I kill, drops i get, and other information about each individual monster and be organized, so I can just go to the page for “monster f” and see if it was a good or bad assignment and things like that. There are hundreds of monsters, so I doubt I could simply make multiple pages. But, I want to be able to do this, as on the following blog:
http://tedbundty.thegrandexchange.com/
Scroll over the above page titles and a list of different sub-pages appear. How do I do this? Any suggestions? Sorry it’s game related >.< This is just a “Test” blog for me so I can learn how to do things.