how do you render white transparent on a layer ?

There are several ways.  Here are a couple.

• If you want to remove the white from a background layer, double-click on the layer to make it a regular layer.
• Select the white area that you want to remove.  The Magic Wand is generally a good tool for this purpose.
• Hit Delete.

Instead of converting the background layer into a regular layer:

• Select the white area using a selection tool.   (If the background of the image is entirely white, you can probably use the Select>Background menu which is available in more recent versions of Elements)
• Use the Eraser tool (E) and brush over the selection.  The white will be removed, leaving a transparency.

What version of Photoshop Elements and operating system are you using?

Are you trying to remove the white background around an object?

Can you post an example of the image?