The list box displays the keys mapped if any.
Press the key or button to map (i.e. Volume up button). Select the keyboard icon button to bring up the soft keyboard if need.
Once a key is pressed, a new row is added. Select the Map button to map the key to a function or macro.
If the key you want to map is the last one of two input keys, select No for mapping the first key and Yes for the second one.
If a macro is selected, select the Macro button to define the actual macro.
Select the Remove option from the drop down list to remove a key mapping.