And no, it should ask you first when you download the World of Minecraft Client, that you need the minecraft.jar file, not the World of Minecraft.jar because when you unzip the womclient, it already includes the World of Minecraft.jar file.  Please look at the tutorial for download the World of Minecraft client.  It should help you.

Scroll down to the bottom of the page and click on tutorial (whatever one that applies to your os (os = operating system))