Importing model files in RoC

Ok, As far as I can see to import .mdx files into the world editor you need to use the import manager (F12) but I can't find this.
I don't know if it's because I'm using RoC world editor, it is then how do I import them normally?
If I had this I could name this then point the skin to the .bmp file.
From here anything is possible, just can't get the models into the map.

I've basically followed a tutorial with a bouncing ball and a skin to go with it.
(It's one of the tutorials on this forum somewhere)
So like I said just need to get it into the map.

Could somebody help me? Thankyou.

Sorry if this has been answered elsewhere but I've scowered the forums for about an hour or so.