Basic baking

Once your settings are ready in the interface, select one or more low-poly mesh in your Maya scene and then hit the big red "Bake texture(s)" button.
Each low poly mesh will have its associated cage and high poly mesh exported/configured and the bake will be processed.

To cancel a baking, simply close the Windows command line window.

Advanced baking

You can manage multiple low poly and high-poly mesh and process them as one by using groups.
In the Maya outliner simply create a group when you put the low-poly meshes and another one with the high-poly meshes.
No need to worry about the names of the meshes present in the group, only the group name matters.

Example :

Then select the group of the low-poly and click on the big red "Bake texture(s)" button.