You can use this module with the following in your ~/.xmonad/xmonad.hs:

 import XMonad.Layout.Simplest

Then edit your layoutHook by adding the Simplest layout:

 myLayouts = Simplest ||| Full ||| etc..
 main = xmonad defaultConfig { layoutHook = myLayouts }

For more detailed instructions on editing the layoutHook see:

XMonad.Doc.Extending