I have used the basic upload a file functionality in my application in spaces. Basically this functionality has a text box and a button where you select the file you want to upload. But when I run my application, the text box is not getting rendered different in each browser and a default text "No files selected to upload" is displayed .
You may want to repost this question in the ADF or WebCenter Portal forum, "Web Space Server" is an entirely different product.
I would suggest to research the ADF forum for this, as the af:fileUpload component is not specific to WebCenter Portal.