Need to create two global varibles. The first currentTab, which will reference the current menu tab being dispalyed with a initial value of null, the second variable is maxZ which will store the z-index and it's initial value is 1.

Need to create a setTabs funstion and then add an event handler to run settabs() functions. within this function the following need to happen:
- declare an empty array named menuTabs
-use getElementsByTagName() method to store all of the elements
-loop through the elements in the all Elems array
-set the currentTab object equal to the first item in the menuTabs array
-add an onclick event handler that runs the showTab function

create the showTab() function and add the following commands:
-set the background color of the currentTab object to white
- increase the value of the maxZ variable by 1
-declare a variable named tabList that references the first ul element nested within this object
- set the z-index value of the tabList object to the value of the maxZ variable
- point the currentTab object to the tabList object
- set background volor of the currentTab ojbject to the color value (221, 221, 255)