Why do some of my stored files show up as a blank white paper icon called Alias? And what should I do with them --are they convertible to a file that can be viewed? Or somehow linked back to the file they are referring to?

Here's what an alias file is:

Create and remove aliases on Mac - Apple Support

In Mac OS X, what is an alias and how does it work?

If you double click on an alias the original file will open. If you Control (right) - click on the alias and select Show Original it will take to you the location of the original file.

If either of the above actions fail to show the original file then either the link is broken or the original file is gone. In that case do a Spotlight search for the name of the alias and see if the original file is anywhere on your hard drive or one an external HD.