Welcome to the Seven Forums
Here are the image #s
1265 verticals show desktop button
1264 horizontal show desktop button
921, 922, 923, 924, that is bottom, right, top, left this is only one part of the taskbar(if it is set to Always combine, high labels
) if it is horizontal and would be the far right and the far left if it is vertical it will be the very top in the very bottom. If set to Never combine
or Combine when taskbar is full
then those numbers above will do the whole taskbar.
If you have your taskbar set to Always combine, high labels
then these images will also be used.
1166 bottom 1168 bottom small icons
1167 top 1169 top small icons
1170 left 1172 left small icons
1171 right 1173 right small icons
Here are two tutorials that may help you. Taskbar - Customize Skin Theme - Customize Custom Themes
Let me know if you need any more help.