You can get step by step information for Creating cubes in Ax 2012 .
http://dynamicsaxforum.blogspot.com/2013/07/creating-cubes-ax-2012.html#!/2013/07/creating-cubes-ax-2012.html
Customizing cubes
http://dynamicsaxforum.blogspot.com/2013/06/customize-cubes-ax-2012.html#!/2013/06/customize-cubes-ax-2012.html
http://dynamicsaxforum.blogspot.com/2013/07/creating-cubes-ax-2012.html#!/2013/07/creating-cubes-ax-2012.html
Customizing cubes
http://dynamicsaxforum.blogspot.com/2013/06/customize-cubes-ax-2012.html#!/2013/06/customize-cubes-ax-2012.html