It sounds like you may be looking at a "System Tray" dock entry.
For a normal dock (whether animated or not), you can right-click an empty space on the dock > select "Add" > "New Shortcut". This should place a default entry icon on the dock and invoke the dock entry properties dialog, which you can then use to select a link and an image.
You can alternatively drag-n-drop any program's executable file onto the dock (providing you have the "drag locking" feature deselected).
I wrote a series of tutorials on ObjectDock Plus, which may help. Here is one that illustrates editing a "non-tabbed" dock http://corkyo.wincustomize.com/Articles.aspx?SID=5463&AID=98644
You can click my name to see the other tutorials listed on my page.