Css And Js Files Of Exetnsion

I am trying to use extension for a multi select drop down list, like http://www.yiiframework.com/extension/echmultiselect/ or http://www.yiiframework.com/extension/emultiselect/ after coping the extension folder under my application directory in extensions or widget as given in extension, i am able to run extensions, but my extensions are not working properly, the reason i observed is the that proper JS and CSS given ins asset/ folder is not getting applied to extensions. so the extensions are not behaving properly.

Do i need to manually include these files on the page? I am adding these extensions in my _form.php view file, which include in create and update view.

kindly help