What is this "Lightroom file" you are referring to? Is it a folder? If so, what is in the folder. If it is a file, what is the extension? Not sure what you are referring to.
It is a lightroom folder which contains the following files:
Lightroom 4 Catalog Previews.Irdata (folder)
Lightroom 4 Catalog (clicking on the icon takes me to lightroom)
Temporary Import Data (file)
Temporary Import Data.db-journal (file)
and then repeats the last two many times...
I greatly appreciate your help
That folder contains your catalog and the previews folder. It needs to be on the new computer. After you install Lightroom on the new computer you can just double-click on that catalog and begin using Lightroom just as you did before. Perhaps the following will give you a better understanding of how to move your Lightroom to a new computer: