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

 import XMonad.Layout.Tabbed

Then edit your layoutHook by adding the Tabbed layout:

 myLayouts = simpleTabbed ||| Full ||| etc..

or, if you want a specific theme for you tabbed layout:

 myLayouts = tabbed shrinkText defaultTheme ||| Full ||| etc..

and then:

 main = xmonad defaultConfig { layoutHook = myLayouts }

The default Tabbar behaviour is to hide it when only one window is open on the workspace. To have it always shown, use one of the layouts or modifiers ending in Always.

For more detailed instructions on editing the layoutHook see:

XMonad.Doc.Extending

You can also edit the default configuration options.

 myTabConfig = defaultTheme { inactiveBorderColor = "#FF0000"
                                   , activeTextColor = "#00FF00"}

and

 mylayout = tabbed shrinkText myTabConfig ||| Full ||| etc..

A tabbed layout with the default xmonad Theme.

This is a minimal working configuration:

 import XMonad
 import XMonad.Layout.DecorationMadness
 main = xmonad defaultConfig { layoutHook = simpleTabbed }