Catagories on Menu?

Hey, so, basically, iv just started with wordpress, never used it before & I’m a little stuck, basically, I want an option on the menu bar for “maps” and I want everything within the maps catagory to show up on that page ( if that makes sense )

Here is a link to my wordpress:

http://minecraftpad.com/

I currently have 2 posts, both with the following catagories:

Maps
Adventure Maps

I also have these as menu options.

The menus are setup as catagories

( image of menu )
https://i.gyazo.com/b51d9837c0b1e97b5091a862ade4d1c3.png

Howeverm, when I click on “Maps” or “Adventure Maps” on the menu, I just get “Error 404 – Article Not Found”

Any idea what I’m doing wrong?