As djadhav says, you are using it right.
Alias names should be short. Should cut out invisible "filler" panels. Should be easy to read and relate to the objects on the screen. I tend to use label names (as this is what the user sees on screen). So rather than:
Aliases.ComboBox
I would have:
Aliases.<Application Name>.<Screen Name>.<ComboBox Lable/Name>
You can't create folders. You shoud be using the pages/screens/sections (whatever is most appropriate really) as the "containers" for objects at lower levels. As I say, if done right, it should be as close to a textual representation of you application (the visible parts) as possible.
The object map = everything ..... in detail!
The alias map = only the bits you NEED .... sensibly named.
One thing you can do, which is sort of like folders, is use multiple instances of a fairly generic object to act as separate containers.
I have a web application I test. It has "tabs" embeded in a section of the web page. But they are not true tabs. So, in my Alias map, I have several copies of the top level tab "container". Each copy is named to represent one of the "tabs" it contains. So the visual feel and representation is retained (ie - the Alias map still reads like what you see on screen) and object location works fine. By using 8 or 9 differently named versions of a single top level object.
I've done it this way since my QTPro days ....
(If your Alias map is a straight copy of your object map .... you're using it completely wrong and might as well not bother with it ...)