Well,
I think you mean that you are having trouble installing a theme, right? If so, the easiest thing to do is to download the theme (makinarma) and unzip it into the autoinstall folder (C:\Program Files\Winstep\AutoInstall), then next time you run Winstep, the theme should be installed.
As far at the addins, from the pic you linked to, I think you'll need quick notes as well as windowblinds.
On the otherhand, if you want to make a theme, using custom graphics etc... I am not the chap to help you
-paul