Login to your cpanel with BLUEHOST
Under the Site Management window (Top Right) you will see FTP manager, click on that.
Next screen click on unlimitedFTP button
Then you should see a dual view window with your computer on the left and bluehost server on the right
On the right double click on public_html folder after you do that double click on either the wordpress folder or wherever you installed wordpress
Next double click on wp-content
Then double click on themes
Now you are in your themes folder on the bluehost server
Drag the theme you downloaded from the left window to the right and that puts the theme into your theme folder.
Then logon to your wordpress blog and go to presentation.
On that page you should see your newly uploaded theme, now just click on it to activate it.
And there ya go.
Hope this helped you
Charles