history center import

 
To import a csv or ASCII file into Metatrader 4 ---you have to go to Tools---History center---import.Then you have to select a symbol in the window on the left of history center and ---navigate to the folder on your PC and click import.Supposing the symbol I want to import is not showing in the left hand window---how do I add new symbols to the left hand side window?  Can anyone help?
 
you can't