I am knaroef, I've made maps before, but this is my first CTF map.
If you've not lived under a rock the last few years, you should know what CTF is.
But in minecraft, there is no flag, there is wool. When you have the wool, place it on the area that is highlighted on this picture:
Map 1 Fortresses
This is just to show what you can do, not to play day after day.