how do I see folder contents in thumbnails

hi, i just bought an imac - I'm used to w7 - and want to [change something if it's even available?] to see thumbnail preview of folder contents, not just gray folders...
i know I can see thumbnails once I've opened folder (but not all, like some movie formats)
is there a way to change this?
I've tried view, window, system preferences, right clicking on folders...

if it's not standard (which would be shocking for a computer that advertises itself as "visual"!)...is there a download somewhere?


thanks

Not sure this will solve all the things you're looking for, but open Show View Options and check or uncheck (reverse whatever is set) "Show Icon Preview". If that makes it worse, you can always change it back.

Also, do you know about Quick Look? Highlight an icon, then hit the Space Bar. Again, it's not exactly what you want, but maybe it's a feature you've not become acquainted with yet.