Hello;
in another thread, it seems that the unzipped template is uploaded to your_site/templates/blue/blue/ and not your_site/templates/blue/.
Check your unzipped template structure on your hard disk. It contains a folder called "blue". Inside you will find two folders called "installation" and "blue". This last folder is the one you have to upload to your templates directory, and not the whole package.
Else, you must have this kind of error message:
Template Error: Couldn't open Template ./templates/blue/whos_online.html