One of the most important features of E-Icons is the possibility to handle icon themes. 

Opening Icon Themes : You can open icon themes by clicking on "Open Icon Theme" from the "E-Icons" menu (E-Icons Themes have .eit extension), by selecting a theme from the list at the bottom of the program (every time E-Icons starts, loads the list of the themes located in its directory) and also by double-clicking on .eit files. After you selected a theme you will be asked for the icons you wish to change (Desktop, Start Menu, Drives, etc...). 
E-Icons comes with several prebuilt icon themes and others can be downloaded (.zip format) from the E-Icons web site. After you unzipped a downloaded theme, copy the contained .icl and .eit files in the E-Icons directory if you want them loaded in the list at the bottom of the program. 

Creating/Saving Icon Themes : You can create/save icon themes by clicking on "Save Icon Theme" from the "E-Icons" menu. The theme you save contains the icons which have been loaded in the program.