Select the object and look into the status line. If it is a group, then ungroup (right-click > ungroup or Ctrl+U or Ctrl+Shift+G) or double-click on it to 'enter' the group. Or you can also hold Ctrl and click on any object to select it, no matter if it's inside a group or not.
If it's not a group, but an 'image', then you cannot access individual parts, because it's not vector-based but just a raster graphic.
