How to add new image to iphone simulator ?

hi. all, as the subject , I want to add new image to simulator , but so far I can not do it .

I also find a thread here :"http://discussions.apple.com/message.jspa?messageID=8125044#8125044" , but I can not do it follow the guide , if some thing I have made wrong ??

thanks to your help .

Regards

Robin