Ahh. Welcome to the world of menu-sets.

'Cos there's just too many options to display all at one, maya uses menu-sets. You can change between these in two ways, firstly the function keys, secondly using the drop-down list-box.

method #1
F2 - Animation
F3 - Modelling
F4 - Dynamics
F5 - Rendering

method #2
Just use the box as illustrated in the attached image.

-Simon.