Good question! Extension Download
In your case you downloaded "vm_white.zip"
Extract the files: in the zip file resides a folder named "vm_white",
upload this folder to the virtuemart theme folder; (with FTP > Filezilla
So you find your theme like this;
set the rights of "theme.config.php" of your theme CHMOD (within Filezilla right mouse button click on this file > file attributes > set 666 or 777
for safety, set the rights back after you are done(, to something like 644).
Go to your Virtuemart administration to change the theme;websitedomain/administrator
> admin tab
(left) > configuration
> site tab
On the right
you find "Layout
" and the text "Select the theme for your Shop
Select your newly uploaded theme here "vm_white
" and apply
Do not forget to set the ""no image" image
" at the site tab > display (left from where you select the theme).
Default images from the theme is / are noimage.png
(=90), noimage100.png (=100) and noimage120.png (=120).
set here your default Category
template to "browse_color
set here your default FLYPAGE
template to "flypage_color
These are slightly changed default pages,
solves some thumbnail issues from the original default template
If you now check your store, you see that your store theme has changed,
your joomla template stays the same.
The virtuemart color themes integrate with the default joomla templates due to color variations.
Can't see the difference?
Check the images: example;
Or try an other theme with a bigger color difference to see what it should do,
try red instead of white in example.
Good examples of images, are the changes in checkout images, rating (stars) and availability.
For the rest (beside color changes), the template stays the default template.
So, in example, the way the checkout process looks stays the same, but only with other colors/images.
Offcourse you can advise the helpfiles aswell.