Check if your MacBook is compatible with Mountain Lion
(which I doubt but you do not provide the exact model you have) check here:
If it does you need to update step by step
buy 10.5 system (hardly available this days - but you may get ot by calling Apple Online Shop
then upgrade to 10.6 - Snow Leopard is available at Apple Online Shop,
then upgrade to Lion via Store app on your computer and then Mountail Lion.
There is no need to get Mac OS X 10.5 (Leopard). This would be an extra step with an expense that is not necessary. You can purchase Mac OS X 10.6 (Snow Leopard) and install it directly over 10.4.
I should point out, though, that there is no MacBook that shipped with 10.4 that will run Mountain Lion. The Mid-2007 MacBook was the last to ship with 10.4 and the highest it will run is Mac OS X 10.7.4 (Lion.)
You can get Lion by contacting Apple's sales group and purchasing a download code. It does require you to have 10.6.8 to do the download however.
Best of luck.
First we need to know which one of the 9 different models of MacBook you have. To see which model you have go to the Apple in the upper left corner and select About This Mac, then click on More Info. When System Profiler comes up check the Model Identifier and post it back here.
The Early 2006 model 1,1 Core Duo can only run a maximum of 10.6 Snow Leopard.
The models Late 2006 Core 2 Duos 2,1 through Early 2008 4,1 can only run a maximum of 10.7 Lion.
The Late 2008 model 5,1 Aluminum Unibody through the Mid 2010 White Unibody model 7,1 can run 10.8 Mountain Lion.