1.
Click on a theme and when your browser asks
select the "Save
to disk" option.
2.
Open Neos MT and go to the configuration window
using the ">>"
button of your contact list, then choose "Tools"
and "Configuration"
from the menu. On the Configuration Window
select "User Interface"
from the list on the left. Use the "Import"
button and find the file that you just downloaded.
Select and open it. The file is not anymore
required, you can delete it if you want.